Author name code: rybak
ADS astronomy entries on 2022-09-14
author:"Rybak, J."
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Title: The SLED project and the dynamics of coronal flux ropes
Authors: Malherbe, Jean-Marie; Mein, Pierre; Sayède, Frédéric;
Rudawy, Pawel; Phillips, Kenneth; Keenan, Francis; Rybák, Jan
Bibcode: 2022AdSpR..70.1562M
Altcode:
Investigations of the dynamics of the hot coronal plasma are crucial
for understanding various space weather phenomena and making in-depth
analyzes of the global heating of the solar corona. We present here
numerical simulations of observations of siphon flows along loops
(simple semi-circular flux ropes) to demonstrate the capabilities of
the Solar Line Emission Dopplerometer (SLED), a new instrument under
construction for imaging spectroscopy. It is based on the Multi-channel
Subtractive Double Pass (MSDP) technique, which combines the advantages
of filters and slit spectrographs. SLED will observe coronal structures
in the forbidden lines of FeX 6374 Å and FeXIV 5303 Å, and will
measure Doppler shifts up to 150 km s-1 at high precision
(50 m s-1) and cadence (1 Hz). It is optimized for studies
of the dynamics of fast evolving events such as flares or Coronal
Mass Ejections (CMEs), as well as for the detection of high-frequency
waves. Observations will be performed with the coronagraph at Lomnický
Štít Observatory (LSO), and will also occur during total solar
eclipses as SLED is a portable instrument.
Title: Narrowband Spikes Observed During the 13 June 2012 Flare in
the 800 - 2000 MHz Range
Authors: Karlický, Marian; Rybák, Ján; Benáček, Jan; Kašparová,
Jana
Bibcode: 2022SoPh..297...54K
Altcode: 2022arXiv220409327K
Narrowband (∼5 MHz) and short-lived (∼0.01 s) spikes with three
different distributions in the 800 - 2000 MHz radio spectrum of the
13 June 2012 flare are detected and analyzed. We designate them as SB
(spikes distributed in a broad band or bands), SZ (spikes distributed
in zebra-like bands) and SBN (spikes distributed in broad and narrow
bands). On analyzing AIA/SDO images of the active region NOAA 11504,
a rough correspondence between groups of the spikes observed at 1000
MHz and peaks in the time profiles of AIA channels taken from the
flare subarea close to the leading sunspot is found. Among the types
of spikes the SZ type is the most interesting because it resembles
zebras. Therefore, using autocorrelation and crosscorrelation methods
we compare SZ and SBN spikes with the typical zebra observed in the
same frequency range. While the ratio of SZ band frequencies with their
frequency separation (220 MHz) is about 4, 5, and 6, in the zebra the
frequency stripe separation is about 24 MHz and the ratio is around
50. Moreover, the bandwidth of SZ bands, which consists of clouds of
narrowband spikes, is much broader than that of zebra stripes. This
comparison indicates that SZ spikes are generated in a different way
from the zebra, but in a similar way to SBN spikes. We successfully fit
the SZ band frequencies by the Bernstein modes. Based on this fitting
we interpret SZ and SBN spikes as those generated in the model of
Bernstein modes. Thus, the magnetic field and plasma density in the SZ
spike source are estimated to be about 79 G and 8.4 × 109
cm−3, respectively.
Title: The Solar Line Emission Dopplerometer project
Authors: Malherbe, Jean-Marie; Mein, Pierre; Sayède, Frédéric;
Rudawy, Pawel; Phillips, Kenneth; Keenan, Francis; Rybák, Jan
Bibcode: 2022ExA....53...83M
Altcode: 2021ExA...tmp..125M; 2021arXiv211001645M
Observations of the dynamics of solar coronal structures are necessary
to investigate space weather phenomena and global heating of the
corona. The profiles of high temperature lines emitted by the hot plasma
are usually integrated by narrow band filters or recorded by classical
spectroscopy. We present in this paper details of a new transportable
instrument (under construction) for imaging spectroscopy: the Solar Line
Emission Dopplerometer (SLED). It uses the Multi-channel Subtractive
Double Pass (MSDP) technique, which combines the advantages of both
filters and narrow slit spectrographs, i.e. high temporal, spatial and
spectral resolutions. The SLED will measure at high cadence (1 Hz)
the line-of-sight velocities (Doppler shifts) of hot coronal loops,
in the forbidden lines of FeX 6374 Å and FeXIV 5303 Å. It will
follow the dynamics of fast evolving events of solar activity such
as flares or Coronal Mass Ejections (CMEs), and also study coronal
heating by short period waves. Observations will be performed with
the coronagraph at the Lomnický Štít Observatory (LSO, in Slovakia)
or during total eclipses. The SLED will also observe the dynamics of
solar prominences in Hα 6563 Å or He D3 5876 Å lines when mounted
on the Białków coronagraph (near Wrocław, Poland). It is fully
compatible with polarimetric measurements by various techniques.
Title: Narrowband Spikes Observed during the 2013 November 7 Flare
Authors: Karlický, Marian; Benáček, Jan; Rybák, Ján
Bibcode: 2021ApJ...910..108K
Altcode: 2021arXiv210401345K
Narrowband spikes have been observed in solar flares for several
decades. However, their exact origin is still discussed. To contribute
to understanding of these spikes, we analyze the narrowband spikes
observed in the 800-2000 MHz range during the impulsive phase of the
2013 November 7 flare. In the radio spectrum, the spikes started with
typical broadband clouds of spikes, and then their distribution in
frequencies changed into unique, very narrow bands having noninteger
frequency ratios. We successfully fitted frequencies of these narrow
spike bands by those, calculating dispersion branches and growth rates
of the Bernstein modes. For comparison, we also analyzed the model
where the narrow bands of spikes are generated at the upper-hybrid
frequencies. Using both models, we estimated the plasma density and
magnetic field in spike sources. Then, the models are discussed,
and arguments in favor of the model with the Bernstein modes are
presented. Analyzing frequency profiles of this spike event by the
Fourier method, we found the power-law spectra with the power-law
indices varying in the -0.8 to -2.75 interval. Because at some times
this power-law index was close to the Kolmogorov spectral index (-5/3),
we propose that the spikes are generated through the Bernstein modes
in turbulent plasma reconnection outflows or directly in the turbulent
magnetic reconnection of solar flares.
Title: Electron Densities in the Solar Corona Measured Simultaneously
in the Extreme Ultraviolet and Infrared
Authors: Dudík, Jaroslav; Del Zanna, Giulio; Rybák, Ján;
Lörinčík, Juraj; Dzifčáková, Elena; Mason, Helen E.; Tomczyk,
Steven; Galloy, Michael
Bibcode: 2021ApJ...906..118D
Altcode: 2020arXiv201109175D
Accurate measurements of electron density are critical for
determination of the plasma properties in the solar corona. We compare
the electron densities diagnosed from Fe XIII lines observed by the
Extreme-Ultraviolet Imaging Spectrometer (EIS) onboard the Hinode
mission with the near-infrared (NIR) measurements provided by the
ground-based Coronal Multichannel Polarimeter (CoMP). To do that, the
emissivity-ratio method based on all available observed lines of Fe
XIII is used for both EIS and CoMP. The EIS diagnostics is further
supplemented by the results from Fe XII lines. We find excellent
agreement, within 10%, between the electron densities measured from both
extreme-ultraviolet and NIR lines. In the five regions selected for
detailed analysis, we obtain electron densities of log(Ne
[cm-3]) = 8.2-8.6. Where available, the background
subtraction has a significant impact on the diagnostics, especially on
the NIR lines, where the loop contributes less than a quarter of the
intensity measured along the line of sight. For the NIR lines, we find
that the line center intensities are not affected by stray light within
the instrument, and recommend using these for density diagnostics. The
measurements of the Fe XIII NIR lines represent a viable method for
density diagnostics using ground-based instrumentation.
Title: The 2017 September 6 Flare: Radio Bursts and Pulsations in
the 22-5000 MHz Range and Associated Phenomena
Authors: Karlický, Marian; Rybák, Ján
Bibcode: 2020ApJS..250...31K
Altcode: 2020arXiv200905756K
For the 2017 September 6 flare (SOL2017-Sep-06T11:53) we present not
only unusual radio bursts but also their interesting time association
with the other flare phenomena observed in extreme ultraviolet (EUV),
white-light, X-ray, and γ-ray emissions. Using our new method based on
wavelets we found quasi-periodic pulsations (QPPs) in several locations
of the whole time-frequency domain of the analyzed radio spectrum
(11:55-12:07 UT and 22-5000 MHz). Among them the drifting QPPs are
new and the most interesting, especially a bidirectional QPP at the
time of the hard X-ray and γ-ray peaks and a sunquake start. In the
pre-impulsive phase we show an unusual drifting pulsation structure
(DPS) in association with the EUV brightenings caused by the interaction
of magnetic ropes. In the flare impulsive phase we found an exceptional
radio burst drifting from 5000 to 800 MHz. In connection with this
drifting burst, we show a U burst at about the onset time of an EUV
writhed structure and a drifting radio burst as a signature of a shock
wave at high frequencies (1050-1350 MHz). In the peak flare phase we
found an indication of an additional energy-release process located
at higher altitudes in the solar atmosphere. These phenomena are
interpreted considering a rising magnetic rope, magnetosonic waves,
and particle beams. Using a density model we estimated the density,
wave velocities, and source heights for the bidirectionally drifting
QPPs, the density for the pre-impulsive DPS and U burst, and the
density and magnetic field strength for the drifting radio burst.
Title: Drifting Pulsation Structure at the Very Beginning of the
2017 September 10 Limb Flare
Authors: Karlický, Marian; Chen, Bin; Gary, Dale E.; Kašparová,
Jana; Rybák, Jan
Bibcode: 2020ApJ...889...72K
Altcode: 2019arXiv191212518K
Drifting pulsation structures (DPSs) are important radio fine structures
usually observed at the beginning of eruptive solar flares. It has been
suggested that DPSs carry important information on the energy release
processes in solar flares. We study DPS observed in an X8.2-class flare
on 2017 September 10 in the context of spatial and spectral diagnostics
provided by microwave, EUV, and X-ray observations. We describe DPS
and its substructures that were observed for the first time. We use a
new wavelet technique to reveal characteristic periods in DPS and their
frequency bands. Comparing the periods of pulsations found in this DPS
with those in previous DPSs, we found new very short periods in the
0.09-0.15 s range. We present Expanded Owens Valley Solar Array images
and spectra of microwave sources observed during the DPS. This DPS at
its very beginning has pulsations in two frequency bands (1000-1300 MHz
and 1600-1800 MHz), which are interconnected by fast drifting bursts. We
show that these double-band pulsations started just at the moment when
the ejected filament splits apart in a tearing motion at the location
where a signature of the flare current sheet later appeared. Using the
standard flare model and previous observations of DPSs, we interpret
these double-band pulsations as a radio signature of superthermal
electrons trapped in the rising magnetic rope and flare arcade at the
moment when the flare magnetic reconnection starts. The results are
discussed in a scenario with the plasmoid in the rising magnetic rope.
Title: Coordinated observations between China and Europe to follow
active region 12709
Authors: González Manrique, S. J.; Kuckein, C.; Gömöry, P.; Yuan,
S.; Xu, Z.; Rybák, J.; Balthasar, H.; Schwartz, P.
Bibcode: 2020IAUS..354...58G
Altcode: 2020IAUS..354...58M; 2019arXiv191208611G
We present the first images of a coordinated campaign to follow active
region NOAA 12709 on 2018 May 13 as part of a joint effort between
three observatories (China-Europe). The active region was close to
disk center and enclosed a small pore, a tight polarity inversion line
and a filament in the chromosphere. The active region was observed
with the 1.5-meter GREGOR solar telescope on Tenerife (Spain) with
spectropolarimetry using GRIS in the He i 10830 Å spectral range
and with HiFI using two broad-band filter channels. In addition,
the Lomnicky Stit Observatory (LSO, Slovakia) recorded the same
active region with the new Solar Chromospheric Detector (SCD) in
spectroscopic mode at Hα 6562 Å. The third ground-based telescope
was located at the Fuxian Solar Observatory (China), where the active
region was observed with the 1-meter New Vacuum Solar Telescope
(NVST), using the Multi-Channel High Resolution Imaging System at
Hα 6562 Å. Overlapping images of the active region from all three
telescopes will be shown as well as preliminary Doppler line-of-sight
(LOS) velocities. The potential of such observations are discussed.
Title: Automatic detection and tracking of coronal bright points in
SDO/AIA images
Authors: Dorotovic, I.; Coelho, A.; Rybak, J.; Mora, A.; Ribeiro,
R.; Kusa, W.; Pires, R.
Bibcode: 2018SunGe..13..129D
Altcode:
The AIA instrument, on-board the SDO satellite, provides high-resolution
and high-cadence solar images since 2010. To extract scientific
knowledge about coronal bright points (CBPs) from those high-resolution
images there is a need for efficient automatic algorithms to detect
and/or track the CBPs. In the last decade other research teams
have developed algorithms to obtain more precise estimations of
the solar rotation profile. However, it is a difficult task because
CBPs may change shape and size over time, yielding great difficulty
to track them. In this work we discuss the usage of two automatic
segmentation algorithms to detect CBPs in SDO/AIA images: (1) using
SunPy and OpenCV in Python and (2) using a Gradient Path Labeling
(GPL) algorithm. Our preliminary tests and results, with a three-day
dataset, show that these algorithms are promising tools to help refine
the solar rotational profile
Title: Fourier Power Spectra of Solar Noise Storms
Authors: Karlický, Marian; Rybák, Ján; Monstein, Christian
Bibcode: 2018SoPh..293..143K
Altcode:
We analyzed three noise storms recorded on 200 - 400 MHz Trieste
Callisto radio spectra on 2 July 2012, 8 July 2012, and 16 July 2012
by the Fourier method. We divided intervals of the noise storms into
five-minute intervals, and in these intervals we computed the mean
Fourier spectra as a function of the wave numbers in the frequency
and height-scale spaces. We found that these Fourier spectra, where
the spectrum from the quiet-activity interval was subtracted, are
power-law spectra. The mean power-law index of these spectra in the
range ln(kz)=[1.8 ,2.9 ] (where kz is the wave
number in the height-scale space) is −1.7 ±0.14 , −1.6 ±0.14 ,
and −1.5 ±0.12 for the 2 July 2012, the 8 July 2012, and the 16
July 2012 noise storms, respectively. It appears that as the number of
Type-I bursts in the studied interval increases, the power-law index
becomes closer to −5 /3 ; this is known as the Kolmogorov spectral
index. The power-law index of the noise storms is very similar to that
of the narrowband dm-spikes found in our previous studies. Furthermore,
we found a break in the power spectra at ln(kz)≈2.9 , and
the mean power-law index values above this break are −2.9 ±0.46 ,
−3.1 ±0.65 , and −3.4 ±0.98 , respectively.
Title: Gradient Path Labelling method and tracking method for
calculation of solar differential rotation using coronal bright points
Authors: Dorotovič, I.; Coelho, A.; Rybák, J.; Mora, A.; Ribeiro, R.
Bibcode: 2018A&C....25..168D
Altcode:
With new space missions, such as Solar Dynamics Observatory (SDO),
solar images are being produced in unprecedented volumes. To derive,
as much as possible, information on evolution of solar activity from
those huge datasets, the scientific community needs a new generation
of software tools for automatic and efficient data processing. In the
last decade, several research teams have been developing tools for
obtaining more precise estimations of the solar rotation profile,
but more are needed to improve knowledge about solar activity. We
applied here a segmentation algorithm called Gradient Path Labelling
(GPL), used originally to identify drusens in medical retinal images,
to detect and track the coronal bright points (CBPs) using images
from the AIA instrument onboard the SDO satellite. The CBPs have a
tendency to change shape and size along time, to disappear and reappear
at a corresponding heliographic position, therefore, decision trees
were also included in the tracking solution. Since our CBP detection
algorithm uses an active region mask to filter out the CBPs, whose
centroid is inside the active regions, the number of identifications
clearly depends on the level of solar activity. Our approach uses the
commonly applied fitting relation to the latitudinal dependence of the
rotational velocity, which resulted in calculation of the optimum fit
parameters as well as the Gegenbauer orthogonal polynomials. Comparison
of these parameters with the results presented in recent papers on this
topic shows that our rotational velocity profile indicates slightly
lower rotational velocities than the profiles obtained with other
approaches. We also calculate the meridional motion of the CBPs, but
comparison with other authors results, clearly show that a 3-day time
interval is too short to estimate the latitudinal dependence of the
CBP meridional motion. Distributions of the rotational velocity and
meridional motion velocity uncertainties show that 85% of uncertainty
values are lower than 1 degree/day. The evaluation of our test results
shows that the applied algorithm is a promising tool that can help to
refine the solar rotational profile.
Title: Oscillations and Waves in Radio Source of Drifting Pulsation
Structures
Authors: Karlický, Marian; Rybák, Ján; Bárta, Miroslav
Bibcode: 2018SoPh..293...62K
Altcode: 2018arXiv180306148K
Drifting pulsation structures (DPSs) are considered to be radio
signatures of the plasmoids formed during magnetic reconnection
in the impulsive phase of solar flares. In the present paper
we analyze oscillations and waves in seven examples of drifting
pulsation structures, observed by the 800 - 2000 MHz Ondřejov
Radiospectrograph. For their analysis we use a new type of oscillation
maps, which give us much more information as regards processes
in DPSs than that in previous analyses. Based on these oscillation
maps, made from radio spectra by the wavelet technique, we recognized
quasi-periodic oscillations with periods ranging from about 1 to 108
s in all studied DPSs. This strongly supports the idea that DPSs are
generated during a fragmented magnetic reconnection. Phases of most
the oscillations in DPSs, especially for the period around 1 s, are
synchronized ("infinite" frequency drift) in the whole frequency range
of DPSs. For longer periods in some DPSs we found that the phases of the
oscillations drift with the frequency drift in the interval from −17
to +287 MHzs−1. We propose that these drifting phases can
be caused (a) by the fast or slow magnetosonic waves generated during
the magnetic reconnection and propagating through the plasmoid, (b) by
a quasi-periodic structure in the plasma inflowing to the reconnection
forming a plasmoid, and (c) by a quasi-periodically varying reconnection
rate in the X-point of the reconnection close to the plasmoid.
Title: Spectroscopic Inversions of the Ca II 8542 Å Line in a
C-class Solar Flare
Authors: Kuridze, D.; Henriques, V.; Mathioudakis, M.; Koza, J.;
Zaqarashvili, T. V.; Rybák, J.; Hanslmeier, A.; Keenan, F. P.
Bibcode: 2017ApJ...846....9K
Altcode: 2017arXiv170800472K
We study the C8.4-class solar flare SOL2016-05-14T11:34 UT using
high-resolution spectral imaging in the Ca II 8542 Å line obtained
with the CRISP imaging spectropolarimeter on the Swedish 1 m Solar
Telescope. Spectroscopic inversions of the Ca II 8542 Å line using
the non-LTE code NICOLE are used to investigate the evolution of
the temperature and velocity structure in the flaring chromosphere. A
comparison of the temperature stratification in flaring and non-flaring
areas reveals strong footpoint heating during the flare peak in the
lower atmosphere. The temperature of the flaring footpoints between
{log} {τ }500 ≈ -2.5 {and} -3.5, where τ 500
is the continuum optical depth at 500 nm, is ∼ 5{--}6.5 {kK} close
to the flare peak, reducing gradually to ∼ 5 {kK}. The temperature in
the middle and upper chromosphere, between {log} {τ }500≈
-3.5 and -5.5, is estimated to be ∼6.5-20 kK, decreasing to preflare
temperatures, ∼5-10 kK, after approximately 15 minutes. However, the
temperature stratification of the non-flaring areas is unchanged. The
inverted velocity fields show that the flaring chromosphere is dominated
by weak downflowing condensations at the formation height of Ca II
8542 Å.
Title: Spectral Characteristics of the He I D3 Line in
a Quiescent Prominence Observed by THEMIS
Authors: Koza, Július; Rybák, Ján; Gömöry, Peter; Kozák, Matúš;
López Ariste, Arturo
Bibcode: 2017SoPh..292...98K
Altcode: 2017arXiv171209255K
We analyze the observations of a quiescent prominence acquired by
the Téléscope Heliographique pour l'Étude du Magnetisme et des
Instabilités Solaires (THEMIS) in the He I 5876 Å (He I D3)
multiplet aiming to measure the spectral characteristics of the He
I D3 profiles and to find for them an adequate fitting
model. The component characteristics of the He I D3 Stokes I
profiles are measured by the fitting system by approximating them with
a double Gaussian. This model yields an He I D3 component
peak intensity ratio of 5.5 ±0.4 , which differs from the value of
8 expected in the optically thin limit. Most of the measured Doppler
velocities lie in the interval ± 5 km s−1, with a standard
deviation of ± 1.7 km s−1 around the peak value of 0.4
km s−1. The wide distribution of the full-width at half
maximum has two maxima at 0.25 Å and 0.30 Å for the He I D3
blue component and two maxima at 0.22 Å and 0.31 Å for the red
component. The width ratio of the components is 1.04 ±0.18 . We show
that the double-Gaussian model systematically underestimates the blue
wing intensities. To solve this problem, we invoke a two-temperature
multi-Gaussian model, consisting of two double-Gaussians, which
provides a better representation of He I D3 that is free
of the wing intensity deficit. This model suggests temperatures of
11.5 kK and 91 kK, respectively, for the cool and the hot component
of the target prominence. The cool and hot components of a typical He
I D3 profile have component peak intensity ratios of 6.6
and 8, implying a prominence geometrical width of 17 Mm and an optical
thickness of 0.3 for the cool component, while the optical thickness of
the hot component is negligible. These prominence parameters seem to
be realistic, suggesting the physical adequacy of the multi-Gaussian
model with important implications for interpreting He I D3
spectropolarimetry by current inversion codes.
Title: Oscillations in the 45 - 5000 MHz Radio Spectrum of the 18
April 2014 Flare
Authors: Karlický, Marian; Rybák, Ján; Monstein, Christian
Bibcode: 2017SoPh..292...94K
Altcode: 2017arXiv170602836K
Using a new type of oscillation map, made from the radio spectra
by the wavelet technique, we study the 18 April 2014 M7.3 flare
(SOL2014-04-18T13:03:00L245C017). We find a quasi-periodic character
of this flare with periods in the range 65 - 115 seconds. At the
very beginning of this flare, in connection with the drifting
pulsation structure (plasmoid ejection), we find that the 65 - 115
s oscillation phase slowly drifts towards lower frequencies, which
indicates an upward propagating wave initiated at the start of the
magnetic reconnection. Many periods (1 - 200 seconds) are found in
the drifting pulsation structure, which documents multi-scale and
multi-periodic processes. On this drifting structure, fiber bursts
with a characteristic period of about one second are superimposed,
whose frequency drift is similar to that of the drifting 65 - 115 s
oscillation phase. We also checked periods found in this flare by the
EUV Imaging Spectrometer (EIS)/Hinode and Interface Region Imaging
Spectrograph (IRIS) observations. We recognize the type III bursts
(electron beams) as proposed, but their time coincidence with the
EIS and IRIS peaks is not very good. The reason probably is that the
radio spectrum is a whole-disk record consisting of all bursts from any
location, while the EIS and IRIS peaks are emitted only from locations
of slits in the EIS and IRIS observations.
Title: Oscillation Maps in the Broadband Radio Spectrum of the 1
August 2010 Event
Authors: Karlický, M.; Rybák, J.
Bibcode: 2017SoPh..292....1K
Altcode: 2016arXiv161102074K
We search for indications of waves in the 25 - 2000 MHz radio spectrum
of the 1 August 2010 event (SOL2010-08-01T08:57:00L075C013), where fast
propagating waves in the solar corona with periods of 181, 69, and 40
seconds were detected in UV observations. Using the wavelet technique,
we construct a new type of oscillation map for selected periods in the
whole domain of the radio spectrum. While an oscillation with a period
of 181 seconds was recognized in the whole 25 - 2000 MHz radio spectrum,
oscillations with periods of 69 and 40 seconds were only confirmed
in the 250 - 870 MHz frequency range. In the 800 - 2000 MHz range we
found periods of 50 and 80 seconds. Moreover, in the 250 - 870 MHz
frequency range, an oscillation with a period of about 420 seconds was
detected. We also made maps of phases of the 181-second oscillations in
order to analyze their frequency drift. At the beginning of the radio
event, the phase of the 181-second oscillation in the 2000 - 500 MHz
frequency range drifts toward lower frequencies. On the other hand,
we found that the phase is nearly synchronous at frequencies 25 - 500
MHz. While the phase drift at higher frequencies can be interpreted
as being caused by the UV wave, the synchronization of the phase
on lower frequencies is explained by the fast electron beams, whose
acceleration is modulated by the UV wave. Owing to this modulation,
the electron beams are accelerated with the period of the UV wave
(181 seconds). These beams propagate upward through the solar corona
and generate the 25 - 500 MHz radio emission with the 181-second
period. The 25 - 500 MHz radio emission, which corresponds to a large
interval of heights in the solar corona, is nearly synchronous because
of the high beam velocity (≈c /3 , where c is the light speed).
Title: Probing the lower solar atmosphere with CRSIP-SST Data
Authors: Hanslmeier, Arnold; Zaqarashvili, Teimuraz; Koza, Julius;
Rybak, Jan
Bibcode: 2017psio.confE.113H
Altcode:
No abstract at ADS
Title: NLTE modeling of a small active region filament observed with
the VTT
Authors: Schwartz, P.; Balthasar, H.; Kuckein, C.; Koza, J.; Gömöry,
P.; Rybák, J.; Heinzel, P.; Kučera, A.
Bibcode: 2016AN....337.1045S
Altcode:
An active region mini-discretionary-filament was observed with the
Vacuum Tower Telescope (VTT) in Tenerife simultaneously in the He
I infrared triplet using the Tenerife Infrared Polarimeter 1 (TIP
1), in Hα with the TESOS Fabry-Pérot interferometer, and in Ca II
8542 Å with the VTT spectrograph. The spectropolarimetric data were
inverted using the HAZEL code and Hα profiles were modelled by solving
a NLTE radiative transfer in a simple isobaric and isothermal 2D slab
irradiated both from its bottom and sides from the solar surface. It was
found that the mini-discretionary-filament is composed of horizontal
fluxtubes, along which the cool plasma of T∼10 000 K can flow with
very large, even supersonic, velocities.
Title: Broadband microwave sub-second pulsations in an expanding
coronal loop of the 2011 August 10 flare
Authors: Mészárosová, H.; Rybák, J.; Kashapova, L.; Gömöry,
P.; Tokhchukova, S.; Myshyakov, I.
Bibcode: 2016A&A...593A..80M
Altcode: 2016arXiv160904217M
Aims: We studied the characteristic physical properties and
behavior of broadband microwave sub-second pulsations observed in
an expanding coronal loop during the GOES C2.4 solar flare on 2011
August 10.
Methods: The complex microwave dynamic spectrum and
the expanding loop images were analyzed with the help of SDO/AIA/HMI,
RHESSI, and the STEREO/SECCHI-EUVI data processing software, wavelet
analysis methods, the GX Simulator tool, and the NAFE method.
Results: We found sub-second pulsations and other different burst
groups in the complex radio spectrum. The broadband (bandwidth about
1 GHz) sub-second pulsations (temporal period range 0.07-1.49 s,
no characteristic dominant period) lasted 70 s in the frequency
range 4-7 GHz. These pulsations were not correlated at their
individual frequencies, had no measurable frequency drift, and zero
polarization. In these pulsations, we found the signatures of fast
sausage magnetoacoustic waves with the characteristic periods of 0.7
and 2 s. The other radio bursts showed their characteristic frequency
drifts in the range of -262-520 MHz s-1. They helped us to
derive average values of 20-80 G for the coronal magnetic field strength
in the place of radio emission. It was revealed that the microwave
event belongs to an expanding coronal loop with twisted sub-structures
observed in the 131, 94, and 193 Å SDO/AIA channels. Their slit-time
diagrams were compared with the location of the radio source at 5.7 GHz
to realize that the EUV intensity of the expanding loop increased just
before the radio source triggering. We reveal two EUV bidirectional
flows that are linked with the start time of the loop expansion. Their
positions were close to the radio source and propagated with velocities
within a range of 30-117 km s-1.
Conclusions: We
demonstrate that periodic regime of the electron acceleration in a model
of the quasi-periodic magnetic reconnection might be able to explain
physical properties and behavior of the sub-second pulsations. The
depolarization process of the microwave emission might be caused by
a plasma turbulence in the radio source. Finally, the observed EUV
flows might be linked with reconnection outflows.
Title: Is it Possible to Use the Green Coronal Line Instead of X rays
to Cancel an Effect of the Coronal Emissivity Deficit in Estimation of
the Prominence Total Mass from Decrease of the EUV-corona Intensities?
Authors: Schwartz, P.; Heinzel, P.; Jejčič, S.; Rybák, J.; Kotrč,
P.; Fárník, F.; Kupryakov, Yu. A.; Deluca, E. E.; Golub, L.; Jibben,
P. R.; Anzer, U.; Tlatov, A. G. .; Guseva, S. A.
Bibcode: 2016ASPC..504...89S
Altcode:
Total masses of six quiescent prominences observed from April through
June 2011 were estimated using multi-spectral observations (in EUV,
X-rays, Hα, and Ca <small>II</small> H). The method for
the total mass estimation is based on the fact that the intensity
of the EUV solar corona at wavelengths below 912 Å is reduced at a
prominence by the absorption in resonance continua (photoionisation)
of hydrogen and possibly by helium and subsequently an amount of
absorbed radiation is proportional to the column density of hydrogen
and helium plasma. Moreover, the deficit of the coronal emissivity in
volume occupied by the cool prominence plasma also contributes to the
intensity decrease. The observations in X-rays which are not absorbed
by the prominence plasma, allow us to separate these two mechanisms
from each other. The X-ray observations of XRT onboard the Hinode
satellite made with the Al-mesh focal filter were used because the
X-ray coronal radiation formed in plasma of temperatures of the order
of 106 K was registered and EUV spectral lines occurring in
the 193, 211 and 335 Å channels of the Atmospheric Imaging Assembly
of the Solar Dynamics Observatory satellite are also formed at such
temperatures. Unfortunately, the Al-mesh filter has a secondary peak
of the transmittance at around 171 Å which causes a contribution
from the EUV corona to the measured data of up to 11 % in the quiet
corona. Thus, absorption in prominence plasma influences XRT X-ray
data when using the Al-mesh filter. On the other hand, other X-ray XRT
filters are more sensitive to plasma of much higher temperatures (log
T of the order of 7), thus observations using these filters cannot
be used together with the AIA observations in the method for mass
estimations. This problem could be solved using observations in the
green coronal line instead of X-rays. Absorption of the green coronal
line by a prominence plasma is negligible and this line is formed at
temperatures of the order of 106 K. We compare values of
the total mass of the prominence observed on 20 October 2012 on the
SE limb estimated when using XRT X-ray observations and observations
in the green coronal line obtained at Kislovodsk Mountain Astronomical
Station of the Pulkovo observatory (Russia).
Title: The Effect of Area Averaging on the Approximated Profile of
the H α Spectral Line
Authors: Bodnárová, M.; Utz, D.; Rybák, J.
Bibcode: 2016ASPC..504...23B
Altcode:
The Hα line is massively used as a diagnostics of the
chromosphere. Often one needs to average the line profile over some
area to increase the signal to noise ratio. Thus it is important to
understand how derived parameters vary with changing approximations. In
this study we investigate the effect of spatial averaging of a selected
area on the temporal variations of the width, the intensity and the
Dopplershift of the Hα spectral line profile. The approximated profile
was deduced from co-temporal observations in five points throughout
the Hα line profile obtained by the tunable Lyot filter installed
on the Dutch Open Telescope. We found variations of the intensity and
the Doppler velocities, which were independent of the size of the area
used for the computation of the area averaged Hα spectral line profile.
Title: Non-LTE Inversion of Spectropolarimetric and Spectroscopic
Observations of a Small Active-region Filament Observed at the VTT
Authors: Schwartz, P.; Balthasar, H.; Kuckein, C.; Koza, J.; Gömöry,
P.; Rybák, J.; Kučera, A.; Heinzel, P.
Bibcode: 2016ASPC..504..205S
Altcode:
An active region mini-filament was observed by VTT simultaneously
in the He<small>I</small> 10 830 Å triplet by the TIP 1
spectropolarimeter, in Hα by the TESOS Fabry-Pérot interferometer, and
in Ca <small>II</small> 8542 Å by the VTT spectrograph. The
spectropolarimetric data were inverted using the HAZEL code and Hα
profiles were modelled solving a NLTE radiative transfer in a simple
isobaric and isothermal 2D slab irradiated both from bottom and
sides. It was found that the mini-filament is composed of horizontal
fluxtubes, along which the cool plasma of T∼10 000 K can flow by
very large - even supersonic - velocities.
Title: The CoMP-S Instrument at the Lomnický Peak Observatory:
Status Report
Authors: Kučera, A.; Ambróz, J.; Gömöry, P.; Habaj, P.; Kavka,
J.; Kozák, M.; Schwartz, P.; Rybák, J.; Tomczyk, S.; Sewell, S.;
Aumiller, P.; Summers, R.; Watt, A.
Bibcode: 2016ASPC..504..321K
Altcode:
The Coronal Multi-channel Polarimeter for Slovakia (CoMP-S) has
been installed at the high-altitude Lomnicky Peak Observatory of the
Astronomical Institute of SAS (2633 m a.s.l.) in 2011. The instrument
was designed and manufactured by HAO/NCAR (Boulder, USA) with a
tunable Lyot filter and polarimeter for visible and near IR spectral
regions. This instrument is proposed for coronagraphic observations of
magnetic and velocity fields in the solar corona and in prominences. A
fundamental upgrade of this instrument has been prepared with pair
of cameras sensitive in the near IR spectral region in a new camera
module. This upgrade is being incorporated to the instrument in course
of the year 2014. In this contribution the technical parameters of the
final configuration of the CoMP-S instrument containing four cameras,
covering both visible and near IR spectral regions, are described. We
also present a potential of the CoMP-S instrument for coronagraphic
spectro-polarimetric observations of the solar corona and prominences
with a capability for sequential measurements of the spectral profiles
of all prominent emission lines in spectral region from 500 to 1100 nm.
Title: Waves and Magnetism in the Solar Atmosphere (WAMIS)
Authors: Ko, Yuan-Kuen; Moses, John; Laming, John; Strachan, Leonard;
Tun Beltran, Samuel; Tomczyk, Steven; Gibson, Sarah; Auchere, Frederic;
Casini, Roberto; Fineschi, Silvano; Knoelker, Michael; Korendyke,
Clarence; McIntosh, Scott; Romoli, Marco; Rybak, Jan; Socker, Dennis;
Vourlidas, Angelos; Wu, Qian
Bibcode: 2016FrASS...3....1K
Altcode:
Comprehensive measurements of magnetic fields in the solar corona have
a long history as an important scientific goal. Besides being crucial
to understanding coronal structures and the Sun’s generation of space
weather, direct measurements of their strength and direction are also
crucial steps in understanding observed wave motions. In this regard,
the remote sensing instrumentation used to make coronal magnetic field
measurements is well suited to measuring the Doppler signature of waves
in the solar structures. In this paper, we describe the design and
scientific values of the Waves and Magnetism in the Solar Atmosphere
(WAMIS) investigation. WAMIS, taking advantage of greatly improved
infrared filters and detectors, forward models, advanced diagnostic
tools and inversion codes, is a long-duration high-altitude balloon
payload designed to obtain a breakthrough in the measurement of
coronal magnetic fields and in advancing the understanding of the
interaction of these fields with space plasmas. It consists of a 20 cm
aperture coronagraph with a visible-IR spectro-polarimeter focal plane
assembly. The balloon altitude would provide minimum sky background and
atmospheric scattering at the wavelengths in which these observations
are made. It would also enable continuous measurements of the strength
and direction of coronal magnetic fields without interruptions from
the day-night cycle and weather. These measurements will be made
over a large field-of-view allowing one to distinguish the magnetic
signatures of different coronal structures, and at the spatial and
temporal resolutions required to address outstanding problems in
coronal physics. Additionally, WAMIS could obtain near simultaneous
observations of the electron scattered K-corona for context and to
obtain the electron density. These comprehensive observations are not
provided by any current single ground-based or space observatory. The
fundamental advancements achieved by the near-space observations of
WAMIS on coronal field would point the way for future ground based
and orbital instrumentation.
Title: Waves and Magnetism in the Solar Atmosphere (WAMIS)
Authors: Strachan, L.; Ko, Y. -K.; Moses, J. D.; Laming, J. M.;
Auchere, F.; Casini, R.; Fineschi, S.; Gibson, S.; Knoelker, M.;
Korendyke, C.; Mcintosh, S.; Romoli, M.; Rybak, J.; Socker, D.;
Tomczyk, S.; Vourlidas, A.; Wu, Q.
Bibcode: 2015IAUS..305..121S
Altcode:
Magnetic fields in the solar atmosphere provide the energy for most
varieties of solar activity, including high-energy electromagnetic
radiation, solar energetic particles, flares, and coronal mass
ejections, as well as powering the solar wind. Despite the fundamental
role of magnetic fields in solar and heliospheric physics, there
exist only very limited measurements of the field above the base of
the corona. What is needed are direct measurements of not only the
strength and orientation of the magnetic field but also the signatures
of wave motions in order to better understand coronal structure, solar
activity, and the role of MHD waves in heating and accelerating the
solar wind. Fortunately, the remote sensing instrumentation used to make
magnetic field measurements is also well suited to measure the Doppler
signature of waves in the solar structures. We present here a mission
concept for the Waves And Magnetism In the Solar Atmosphere (WAMIS)
experiment which is proposed for a NASA long-duration balloon flight.
Title: Dual instrument for Flare and CME onset observations -
Double solar Coronagraph with Solar Chromospheric Detector and
Coronal Multi-channel Polarimeter at Lomnicky stit Observatory
Authors: Kucera, Ales; Tomczyk, Steven; Rybak, Jan; Sewell, Scott;
Gomory, Peter; Schwartz, Pavol; Ambroz, Jaroslav; Kozak, Matus
Bibcode: 2015IAUGA..2246687K
Altcode:
We report on unique dual instrument developed for simultaneous
measurements of velocity and magnetic fields in the solar chromosphere
and corona. We describe the technical parameters and capability of
the Coronal Multi-channel Polarimeter (CoMP-S) and Solar Chromospheric
detector (SCD) mounted at the Double solar coronagraph at Lomnicky Stit
Observatory and working simultaneously with strictly parallel pointing
of both coronagraphs. The CoMP-S is 2D spectropolarimeter designed
for observations of VIS and near-IR emission lines of prominences
and corona with operating spectral range: 500 - 1100 nm, sequential
measurement of several VIS and near-IR lines. Its field of view is
14 arcmin x 11 arcmin. It consists of 4-stage calcite Lyot filter
followed by the ferro-liquid crystal polarizer and four cameras (2
visible, 2 infrared). The capability is to deliver 2D full Stokes I,
Q, U, V, using registration with 2 IR cameras (line + background) and
2 VIS cameras (line + background) SCD is a single beam instrument to
observe bright chromosphere. It is a combination of tunable filter and
polarimeter. Spectral resolution of the SCD ranges from 0.046 nm for
observations of the HeI 1083 nm line up to to 25 pm is for observation
of the HeI 587.6 nm line. The birefringent filter of the SCD has high
spectral resolution, as well as spatial resolution (1.7 arcseconds)
and temporal resolution (10 seconds) First results are also reported
and discussed.
Title: Waves and Magnetism in the Solar Atmosphere (WAMIS)
Authors: Ko, Y. K.; Auchere, F.; Casini, R.; Fineschi, S.; Gibson,
S. E.; Knoelker, M.; Korendyke, C.; Laming, J. M.; Mcintosh, S. W.;
Moses, J. D.; Romoli, M.; Rybak, J.; Socker, D. G.; Strachan, L.;
Tomczyk, S.; Vourlidas, A.; Wu, Q.
Bibcode: 2014AGUFMSH53B4221K
Altcode:
Magnetic fields in the solar atmosphere provide the energy for most
varieties of solar activity, including high-energy electromagnetic
radiation, solar energetic particles, flares, and coronal mass
ejections, as well as powering the solar wind. Despite the fundamental
role of magnetic fields in solar and heliospheric physics, there
exists only very limited measurements of the field above the base of
the corona. What is needed are direct measurements of not only the
strength and orientation of the magnetic field but also the signatures
of wave motions in order to better understand coronal structure,
solar activity and the role of MHD waves in heating and accelerating
the solar wind. Fortunately, the remote sensing instrumentation used
to make magnetic field measurements is also well suited for measuring
the Doppler signature of waves in the solar structures. With this
in mind, we are proposing the WAMIS (Waves and Magnetism in the
Solar Atmosphere) investigation. WAMIS will take advantage of greatly
improved infrared (IR) detectors, forward models, advanced diagnostic
tools and inversion codes to obtain a breakthrough in the measurement
of coronal magnetic fields and in the understanding of the interaction
of these fields with space plasmas. This will be achieved with a high
altitude balloon borne payload consisting of a coronagraph with an IR
spectro-polarimeter focal plane assembly. The balloon platform provides
minimum atmospheric absorption and scattering at the IR wavelengths in
which these observations are made. Additionally, a NASA long duration
balloon flight mission from the Antarctic can achieve continuous
observations over most of a solar rotation, covering all of the key
time scales for the evolution of coronal magnetic fields. With these
improvements in key technologies along with experience gained from
current ground-based instrumentation, WAMIS will provide a low-cost
mission with a high technology readiness leve.
Title: Magnetoacoustic Waves Propagating along a Dense Slab and
Harris Current Sheet and their Wavelet Spectra
Authors: Mészárosová, Hana; Karlický, Marian; Jelínek, Petr;
Rybák, Ján
Bibcode: 2014ApJ...788...44M
Altcode:
Currently, there is a common endeavor to detect magnetoacoustic
waves in solar flares. This paper contributes to this topic using an
approach of numerical simulations. We studied a spatial and temporal
evolution of impulsively generated fast and slow magnetoacoustic
waves propagating along the dense slab and Harris current sheet using
two-dimensional magnetohydrodynamic numerical models. Wave signals
computed in numerical models were used for computations of the temporal
and spatial wavelet spectra for their possible comparison with those
obtained from observations. It is shown that these wavelet spectra allow
us to estimate basic parameters of waveguides and perturbations. It was
found that the wavelet spectra of waves in the dense slab and current
sheet differ in additional wavelet components that appear in association
with the main tadpole structure. These additional components are new
details in the wavelet spectrum of the signal. While in the dense slab
this additional component is always delayed after the tadpole head, in
the current sheet this component always precedes the tadpole head. It
could help distinguish a type of the waveguide in observed data. We
present a technique based on wavelets that separates wave structures
according to their spatial scales. This technique shows not only
how to separate the magnetoacoustic waves and waveguide structure in
observed data, where the waveguide structure is not known, but also
how propagating magnetoacoustic waves would appear in observations
with limited spatial resolutions. The possibilities detecting these
waves in observed data are mentioned.
Title: On Dynamics of G-Band Bright Points
Authors: Bodnárová, M.; Utz, D.; Rybák, J.
Bibcode: 2014SoPh..289.1543B
Altcode: 2013arXiv1312.5464B
Various parameters describing the dynamics of G-band bright points
(GBPs) were derived from G-band images, acquired by the Dutch Open
Telescope (DOT), of a quiet region close to the disk center. Our
study is based on four commonly used diagnostics (effective velocity,
change in the effective velocity, change in the direction angle, and
centrifugal acceleration) and two new ones (rate of motion and time lag
between recurrence of GBPs). The results concerning the commonly used
parameters are in agreement with previous studies for a comparable
spatial and temporal resolution of the used data. The most probable
value of the effective velocity is ∼ 0.9 km s−1,
whereas we found a deviation of the effective velocity distribution
from the expected Rayleigh function for velocities in the range from
2 to 4 km s−1. The change in the effective velocity
distribution is consistent with a Gaussian one with FWHM=0.079 km
s−2. The distribution of the centrifugal acceleration
exhibits a highly exponential nature (a symmetric Gaussian centered
at the zero value). To broaden our understanding of the dynamics of
GBPs, two new parameters were defined: the real displacement between
their appearance and disappearance (rate of motion) and the frequency
of their recurrence at the same locations (time lag). For ∼ 45 % of
the tracked GBPs, their displacement was found to be small compared to
their size (the rate of motion smaller than one). The locations of the
tracked GBPs mainly cover the boundaries of supergranules representing
the network, and there is no significant difference in the locations
of GBPs with small (m<1) and large (m>2) values of the rate of
motion. We observed a difference in the overall trend of the obtained
distribution for the values of the time lag smaller (slope of the trend
line being −0.14) and greater (−0.03) than ∼ 7 min. The time
lags mostly lie within the interval of ∼ 2 - 3 min, with those up to
∼ 4 min being more abundant than longer ones. Results for both new
parameters indicate that the locations of different dynamical types
of GBPs (stable/farther traveling or with short/long lifetimes) are
bound to the locations of more stable and long-living magnetic field
concentrations. Thus, the disappearance/reappearance of the tracked
GBPs cannot be perceived as the disappearance/reappearance of their
corresponding magnetic field concentrations.
Title: Inferring spectral characteristics of the Hα spectral line
observed by the DOT Lyot filter
Authors: Koza, J.; Rybák, J.; Gömöry, P.; Kučera, A.
Bibcode: 2014CoSka..44...43K
Altcode:
A tunable Lyot filter can serve as a spectroscopic device rendering
wide-field 2-D pseudospectroscopy of solar structures and follow-up
crude reconstruction of a spectral line profile at each pixel within the
field of view. We developed a method of inferring of the Doppler shift,
the core intensity, the core width, and the core asymmetry of the Hα
spectral line observed by the Lyot filter installed on the Dutch Open
Telescope (DOT). The spectral characteristics are inferred through the
fitting of five intensity samples, separated from each other by 0.35 Å,
by a 4th-order polynomial, a Gaussian, and a parabola. We
use the atlas Hα profile as a reference in estimating deviations
of the derived spectral characteristics. The Gaussian is the most
preferable means for measurements of the Doppler shift with deviations
smaller than 1 km s-1. When using the 4th-order
polynomial, deviations are within the interval ±2.5 km s-1,
but it renders comparable deviations of the core intensity and the
width as the Gaussian. The deviations are largely insensitive to the
shape of the filter transmission, but depend mostly non-linearly on
the Doppler shift. Therefore, they do not cancel out if the spectral
characteristics are represented by their relative variations. Results
can be used as corrections of spectral characteristics extracted from
area-averaged Hα profiles acquired by the DOT Lyot filter.
Title: Transmission profile of the Dutch Open Telescope Hα Lyot
filter
Authors: Koza, J.; Hammerschlag, R. H.; Rybák, J.; Gömöry, P.;
Kučera, A.; Schwartz, P.
Bibcode: 2014AN....335..409K
Altcode: 2017arXiv171209253K
Context Accurate knowledge of the spectral transmission profile of
a Lyot filter is important, in particular in comparing observations
with simulated data. The paper summarizes available facts about the
transmission profile of the Dutch Open Telescope (DOT) Hα Lyot filter
pointing to a discrepancy between sidelobe-free Gaussian-like profile
measured spectroscopically and signatures of possible leakage of
parasitic continuum light in DOT Hα images. We compute wing-to-center
intensity ratios resulting from convolutions of Gaussian and square
of the sinc function with the Hα atlas profile and compare them with
the ratios derived from observations of the quiet Sun chromosphere at
disk center. We interpret discrepancies between the anticipated and
observed ratios and the sharp limb visible in the DOT Hα image as an
indication of possible leakage of parasitic continuum light. A method
suggested here can be applied also to indirect testing of transmission
profiles of other Lyot filters. We suggest two theoretical transmission
profiles of the DOT Hα Lyot filter which should be considered as the
best available approximations. Conclusive answer can only be given by
spectroscopic re-measurement of the filter.
Title: Coronal Multi-channel Polarimeter at the Lomnicky Peak
Observatory
Authors: Schwartz, P.; Ambroz, J.; Gömöry, P.; Kozák, M.; Kučera,
A.; Rybák, J.; Tomczyk, S.; Sewell, S.; Aumiller, P.; Summers, R.;
Sutherland, L.; Watt, A.
Bibcode: 2014IAUS..300..521S
Altcode:
Coronal Multi-channel Polarimeter (CoMP-S), developed by HAO/NCAR, has
been introduced to regular operation at the Lomnicky Peak Observatory
(High Tatras in northern Slovakia, 2633 m a.s.l.) of the Astronomical
Institute of Slovak Academy of Sciences. We present here the technical
parameters of the current version of the instrument and its potential
for observations of prominences in the visual and near-IR spectral
regions. The first results derived from observations of prominences
in the Hα emission line taken during a coordinated observing campaign
of several instruments in October 2012 are shown here.
Title: Space- and Ground-based Coronal Spectro-Polarimetry
Authors: Fineschi, Silvano; Bemporad, Alessandro; Rybak, Jan;
Capobianco, Gerardo
Bibcode: 2014cosp...40E.868F
Altcode:
This presentation gives an overview of the near-future perspectives of
ultraviolet and visible-light spectro-polarimetric instrumentation
for probing coronal magnetism from space-based and ground-based
observatories. Spectro-polarimetric imaging of coronal emission-lines
in the visible-light wavelength-band provides an important diagnostics
tool of the coronal magnetism. The interpretation in terms of Hanle and
Zeeman effect of the line-polarization in forbidden emission-lines
yields information on the direction and strength of the coronal
magnetic field. As study case, this presentation will describe the
Torino Coronal Magnetograph (CorMag) for the spectro-polarimetric
observation of the FeXIV, 530.3 nm, forbidden emission-line. CorMag
- consisting of a Liquid Crystal (LC) Lyot filter and a LC linear
polarimeter - has been recently installed on the Lomnicky Peak
Observatory 20cm Zeiss coronagraph. The preliminary results from CorMag
will be presented. The linear polarization by resonance scattering
of coronal permitted line-emission in the ultraviolet (UV)can be
modified by magnetic fields through the Hanle effect. Space-based
UV spectro-polarimeters would provide an additional tool for the
disgnostics of coronal magnetism. As a case study of space-borne
UV spectro-polarimeters, this presentation will describe the future
upgrade of the Sounding-rocket Coronagraphic Experiment (SCORE) to
include the capability of imaging polarimetry of the HI Lyman-alpha,
121.6 nm. SCORE is a multi-wavelength imager for the emission-lines,
HeII 30.4 nm and HI 121.6 nm, and visible-light broad-band emission
of the polarized K-corona. SCORE has flown successfully in 2009. This
presentation will describe how in future re-flights SCORE could observe
the expected Hanle effect in corona with a HI Lyman-alpha polarimeter.
Title: Search for Alfvén waves in a bright network element observed
in Hα
Authors: Koza, J.; Sütterlin, P.; Gömöry, P.; Rybák, J.;
Kučera, A.
Bibcode: 2013CoSka..43....5K
Altcode: 2013arXiv1304.4027K
Alfvén waves are considered as potential transporters of energy
heating the solar corona. We seek spectroscopic signatures of the
Alfvén waves in the chromosphere occupied by a bright network element,
investigating temporal variations of the spectral width, intensity,
Dopplershift, and the asymmetry of the core of the Hα spectral
line observed by the tunable Lyot filter installed on the Dutch Open
Telescope. The spectral characteristics are derived through the fitting
of five intensity samples, separated from each other by 0.35 Å, by a
4th-order polynomial. The bright network element displays
the most pronounced variations of the Dopplershift varying from 0 to 4
km s-1 about the average of 1.5 km s-1. This fact
implies a persistent redshift of the Hα core with a redward asymmetry
of about 0.5 km s-1, suggesting an inverse-C bisector. The
variations of the core intensity up to ±10 % and the core width up to
±5 % about the respective averages are much less pronounced, but still
detectable. The core intensity variations lag behind the Dopplershift
variations about 2.1 min. The Hα core width tends to correlate with
the Dopplershift and anticorrelate with the asymmetry, suggesting that
more redshifted Hα profiles are wider and the broadening of the Hα
core is accompanied with a change of the core asymmetry from redward
to blueward. We also found a striking anticorrelation between the
core asymmetry and the Dopplershift, suggesting a change of the core
asymmetry from redward to blueward with an increasing redshift of the
Hα core. The data and the applied analysis do not show meaningful
tracks of Alfvén waves in the selected network element.
Title: A quiescent prominence observed in the Hα line by the COMP-S
instrument at the Lomnický Peak Observatory
Authors: Schwartz, P.; Rybák, J.; Kučera, A.; Kozák, M.; Ambróz,
J.; Gömöry, P.
Bibcode: 2012CoSka..42..135S
Altcode:
A prominence above the NEE limb was observed by the COMP-S instrument
attached to the ZEISS coronagraph located at the Lomnický Peak
Observatory. Observations were carried out on Nov 2, 2011 between
14:01:13 and 14:11:34 UT. The filter of the instrument was tuned during
measurements sequentially in five wavelengths within the profile of
the Hα line: 0, ±1, ±2 Å around 6563 Å. FWHM of the transmission
function of the filter was ∼0.4Å at these wavelengths. Data were
not absolutely calibrated, therefore they could be fitted using only a
simple cloud model (1D geometry, a complete frequency redistribution,
a source function independent of the optical depth) to diagnose the
prominence plasma. As five wavelength points in the profile were not
enough for an automatic fitting, five positions at the prominence were
chosen for the analysis. Observed data from the five positions were
simulated using the cloud model and groups of different models were
found for each position. It means that the wavelength scale of a step
as large as 1 Å when used for the Hα line is not fine enough for
estimation of a correct and unique model. Simulating observations
using three different finer wavelength scales it was found that
the wavelength scale with a step of 0.3 Å and even more finer in
the line core (step of 0.1 Å) is already suitable for more precise
and unambiguous plasma diagnostics. We also show that for correct
plasma diagnostics it is crucial to take into account an effect of a
finite width of the transmission function of the filter. If observed
data were fitted irrespectively of this important effect, an error
in estimated model parameters could exceed even 100 %, except for
the Doppler velocities, for which the error would be much smaller,
e.g. for velocities up to 20 km s-1 the error is below 1 %.
Title: Dependence of Velocity Distributions of Small-Scale Magnetic
Fields Derived from Hinode/SOT G-band Filtergrams on the Temporal
Resolution of the Used Data Sets
Authors: Utz, D.; Hanslmeier, A.; Muller, R.; Veronig, A.; Rybák,
J.; Muthsam, H.
Bibcode: 2012ASPC..454...55U
Altcode:
The dynamics of isolated small-scale fields in terms of velocities of
magnetic bright points (MBPs) is addressed in this contribution. The
empirically determined linear relation between the observed width
parameter for the Rayleigh velocity distribution of MBPs versus the
temporal cadence of the acquired data is studied by simulations and a
simple analytical model. The results of the model and the simulation
agree with the found relation for the observations. The conclusion we
draw from the model is that there may be no characteristic velocity
for MBPs at all.
Title: Magnetoacoustic Wave Trains in the 11 July 2005 Radio Event
with Fiber Bursts
Authors: Mészárosová, H.; Karlický, M.; Rybák, J.
Bibcode: 2012esrs.book...87M
Altcode:
A dm-radio emission with fiber bursts observed on 11 July 2005 was
analyzed using wavelet filtration and spectral methods. In filtered
radio spectra we found structures with different characteristic
period P and frequency drift FD: i) fiber substructures (composed
of dot emissions) with P 1≈ 0.5 s, FD1=-
87 MHz s-1 on average, ii) fiber structures with
P 2≈1.9 s, and iii) drifting structures with P
3≈81.4 s, FD2=- 8.7, + 98.5, and - 21.8 MHz
s-1. In the wavelet spectra we recognized patterns having
the form of tadpoles. They were detected with the same characteristic
periods P as found for the filtered structures. The frequency
drift of the tadpole heads is found to be equal to the frequency
drift of some groups of fibers for the long-period wavelet tadpoles
(P 3) and to the frequency drift of individual fibers for
the short-period tadpoles (P 2). Considering these wavelet
tadpoles as signatures of propagating magnetoacoustic wave trains,
the results indicate the presence of several wave trains in the fibers'
source. While the long-period wave trains trigger or modulate a whole
group of fibers, the short-period ones look like being connected with
individual fiber bursts. This result supports the model of fibers based
on magnetoacoustic waves. Using a density model of the solar atmosphere
we derived the velocities of the magnetoacoustic waves, 107 and 562 km
s-1, and setting them equal to the Alfvén ones we estimated
the magnetic field in the source of fiber bursts as 10.7 and 47.8 G.
Title: Magnetoacoustic Wave Trains in the 11 July 2005 Radio Event
with Fiber Bursts
Authors: Mészárosová, H.; Karlický, M.; Rybák, J.
Bibcode: 2011SoPh..273..393M
Altcode: 2011SoPh..tmp..128M; 2011SoPh..tmp..183M; 2011SoPh..tmp..252M
A dm-radio emission with fiber bursts observed on 11 July 2005 was
analyzed using wavelet filtration and spectral methods. In filtered
radio spectra we found structures with different characteristic
period P and frequency drift FD: i) fiber substructures (composed
of dot emissions) with P1≈ 0.5 s, FD1=−
87 MHz s−1 on average, ii) fiber structures
with P2≈1.9 s, and iii) drifting structures with
P3≈81.4 s, FD2=− 8.7, + 98.5, and − 21.8 MHz
s−1. In the wavelet spectra we recognized patterns having
the form of tadpoles. They were detected with the same characteristic
periods P as found for the filtered structures. The frequency
drift of the tadpole heads is found to be equal to the frequency
drift of some groups of fibers for the long-period wavelet tadpoles
(P3) and to the frequency drift of individual fibers for
the short-period tadpoles (P2). Considering these wavelet
tadpoles as signatures of propagating magnetoacoustic wave trains,
the results indicate the presence of several wave trains in the fibers'
source. While the long-period wave trains trigger or modulate a whole
group of fibers, the short-period ones look like being connected with
individual fiber bursts. This result supports the model of fibers
based on magnetoacoustic waves. Using a density model of the solar
atmosphere we derived the velocities of the magnetoacoustic waves,
107 and 562 km s−1, and setting them equal to the Alfvén
ones we estimated the magnetic field in the source of fiber bursts as
10.7 and 47.8 G.
Title: The LSO/KSO Hα prominence catalogue: cross-calibration of data
Authors: Rybák, J.; Gömöry, P.; Mačura, R.; Kučera, A.; Rušin,
V.; Pötzi, W.; Baumgartner, D.; Hanslmeier, A.; Veronig, A.;
Temmer, M.
Bibcode: 2011CoSka..41..133R
Altcode:
We present work on the extension of the homogeneous prominence
catalogue created for the epoch 1967 — 2009 at the Lomnicky Peak
Observatory (LSO) by incorporating new data acquired at the Kanzelhöhe
Observatory for Solar and Environmental Research (KSO). We use data of
20 Hα prominences observed almost simultaneously at both observatories
during four days in August/September 2009 to analyze the significance
of differences of the determined parameters used in the Hα prominence
catalogue. A reduction of the data from KSO and adaptation of the
resulting parameters to fit the parameters of the LSO catalogue confirm
that no special homogenization is needed to create a common catalogue
data set. Thus, we justified that the LSO catalogue could be extended
onward in the future using a more comprehensive database of observations
from KSO.
Title: Separation of solar radio bursts in a complex spectrum
Authors: Mészárosová, Hana; Rybák, Ján; Karlický, Marian;
Jiřička, Karel
Bibcode: 2011IAUS..274..150M
Altcode:
Radio spectra, observed during solar flares, are usually very complex
(many bursts and fine structures). We have developed a new method to
separate them into individual bursts and analyze them separately. The
method is used in the analysis of the 0.8-2.0 GHz radio spectrum of the
April 11, 2001 event, which was rich in drifting pulsating structures
(DPSs). Using this method we showed that the complex radio spectrum
consists of at least four DPSs separated with respect to their different
frequency drifts (-115, -36, -23, and -11 MHz s-1). These
DPSs indicate a presence of at least four plasmoids expected to be
formed in a flaring current sheet. These plasmoids produce the radio
emission on close frequencies giving thus a mixture of superimposed
DPSs observed in the radio spectrum.
Title: Separation of drifting pulsating structures in a complex
radio spectrum of the 2001 April 11 event
Authors: Mészárosová, H.; Rybák, J.; Karlický, M.
Bibcode: 2011A&A...525A..88M
Altcode:
Aims: We present new method of separating a complex radio
spectrum into single radio bursts. The method is used in the analysis
of the 0.8-2.0 GHz radio spectrum of the 2001 April 11 event, which
was rich in drifting pulsating structures.
Methods: The method
is based on the wavelet analysis technique, which separates different
spatial-temporal components (radio bursts) that are difficult to
recognize in the original radio spectrum.
Results: We show with
this method that the complex radio spectrum observed during the 2001
April 11 event consists of at least four drifting pulsating structures
(DPSs). These structures were separated with respect to their different
frequency drifts. The DPSs indicate at least four plasmoids that are
supposed to be formed in a flaring current sheet.
Title: Heating of the quiet solar corona from measurements of the
FET/TESIS instrument on-board the KORONAS-FOTON satellite
Authors: Rybák, J.; Gömöry, P.; Benz, A.; Bogachev, P.; Brajša, R.
Bibcode: 2010nspm.conf..107R
Altcode:
The paper presents the first results of the observations of time
evolution of the quiet solar corona brightenings obtained due to
very rapid photography of the corona with full-disk EUV telescopes
of the FET/TESIS instrument onboard the KORONA FOTON satellite. The
measurements were performed simultaneously in the emission of the Fe
IX / X 17.1 and Fe VIII 13.1 spectral lines with 10 second temporal
cadence and spatial scale of 1.7 arc seconds within one hour. This
test observation, carried out on 15 July 2009, was analyzed in order
to determine whether this type of observation can be used to identify
individual microevents in the solar corona heating that are above the
tresholds of spatial and temporal resolutions of the observations
of non-active regions in the solar atmosphere. For this purpose,
a simple method was used involving cross-correlation of the plasma
emission time evolution at different temperatures, each time from
observations of identical elements. The results obtained are confronted
with the expected observable manifestations of the corona heating
via nanoflares. TESIS is a set of instruments for the Sun photography
developed in the Lebedev Physics Institute of the Russian Academy of
Sciences that was launched into orbit in January 2009.
Title: Koronálny multikanálový polarimeter pre observatórium
Lomnický štít Title: Koronálny multikanálový polarimeter
pre observatórium Lomnický štít Title: Coronal multichannel
polarimeter for Lomnický štít Observatory.
Authors: Rybák, J.; Ambróz, J.; Gömöry, P.; Kozák, M.; Kučera,
A.; Tomczyk, S.; Sewell, S.; Summers, R.; Sutherland, L.; Watt, A.
Bibcode: 2010nspm.conf..196R
Altcode:
The contribution presents the process of development and preparation
of the Coronal Multi-channel Polarimeter (COMP-S) for the Lomnický
štít Observatory of the SAS Astronomy Institute. The design of the
device is based on the experience gained in recent years with the CoMP
(High Altitude Observatory / NCAR; Boulder, USA) instrument. The device
will be a combination of two main optical components: the Lyot tunable
filter and polarimeter, and is prepared specifically for one of the
20 cm Zeiss coronagraph at the Lomnický štít Observatory where it
will be installed in 2011. CoMP-S will differ from its predecessor
in several respects. The most important difference is that CoMP-S
will be able to observe the corona and chromospheric emission lines
in the wavelength range from 530 to 1083 nm. This feature will be
achieved using superachromatic wave plates and dichroic polarizers
with wide bandwidth. Furthermore, in the CoMP-S instrument new SWIFT
liquid crystals of Meadowlark Optics company will be used as variable
retarders instead of nematic liquid crystal retarders (LCVR) which
will considerably shorten the measuring process. Ferroelectric liquid
crystals will provide measurements of the full Stokes vector with nearly
optimal polarization throughout the whole instrument bandwidth. Recently
developed sCMOS cameras are to provide diffraction limit resolution of
observations, with the 860x680 arc second field and 30-frames-per-second
cadence. The device will be used in the Astronomical Observatory of SAS
at Lomnický štít primarily for spectrum polarimetry of prominences
and coronal loops of the active solar regions.
Title: Observatórium Lomnický štít - meteorológia a slnečná
astrofyzika Title: Observatórium Lomnický štít - meteorológia
a slnečná astrofyzika Title: Lomnický štít Observatory -
meteorology and solar astrophysics.
Authors: Rybák, J.; Mačura, R.; Bendík, P.; Bochníček, O.;
Horecká, V.
Bibcode: 2010nspm.conf..191R
Altcode:
The paper presents statistical results obtained in the analysis of
long-term series of meteorological observations of temperature, wind
speed and wind direction, and daylight length that were measured
in the period 1964-2009 at the SHMI Meteorological Observatory
located at the Lomnický štít mountain peak. In relation to these
meteorological data, the contribution also presents statistical results
for time scales of various types of solar prominence and solar corona
observations at the Lomnický štít Astronomical Observatory in the
period 1980-2009. The obtained results were used to characterize the
observatory from meteorological perspective presenting mainly the
range and quality of observing conditions suitable for solar activity
observations. The results show that observing conditions allow for
observation of prominences in approximately one third of the days in
a year, and observation of the emission corona in approximately one
fifth of the days in a year. The contribution also documents the use of
the obtained results in preparation of new post-focal instruments for
solar corona monitoring, i. e. the coronal multipolarimeter (COMP-S)
that is at present under construction. Effects of local warming of
the Earth's atmosphere are tested in a statistical analysis of the
meteorological data collected in the period 1964-2009. In this period,
a marked local warming occured at Lomnický štít with increases in
the minimal daily temperature 0.90°C and maximal daily temperature
1.84°C, and the mean value of these quantities raising by 1.21°C.
Title: Dynamika fotosférických jasných bodov v G-páse odvodená
použitím dvoch plne automatických algoritmov Title: Dynamika
fotosférických jasných bodov v G-páse odvodená použitím dvoch
plne automatických algoritmov Title: Dynamics of photospheric bright
points in G-band derived from two fully automated algorithms.
Authors: Bodnárová, M.; Rybák, J.; Hanslmeier, A.; Utz, D.
Bibcode: 2010nspm.conf...25B
Altcode:
Concentrations of small-scale magnetic field in the solar photosphere
can be identified in the G-band of the solar spectrum as bright
points. Studying the dynamics of the bright points in the G-band
(BPGBs) can also help in addressing many issues related to the
problem of the solar corona heating. In this work, we have used
a set of 142 specled images in the G-band taken by the Dutch Open
Telescope (DOT) on 19 October 2005 to make a comparison of two fully
automated algorithms identifying BPGBs: an algorithm developed by Utz
et al. (2009, 2010), and an algorithm developed following the work
of Berger et al. (1995, 1998). We then followed in time and space
motion of the BPGBs identified by both algorithms and constructed the
distributions of their lifetimes, sizes and speeds. The results show
that both algorithms give very similar results for the BPGB lifetimes
and speeds, but their results vary significantly for the sizes of the
identified BPGBs. This difference is due to the fact that in the case of
the Berger et al. identification algorithm no additional criteria were
applied to constrain the allowed BPGB sizes. As a result in further
studies of the BPGB dynamics we will prefer to use the Utz algorithm
to identify and track BPGBs.
Title: North-south asymmetry of Ca II K regions determined from OAUC
spectroheliograms: 1996 - 2006
Authors: Dorotovič, I.; Rybák, J.; Garcia, A.; Journoud, P.
Bibcode: 2010nspm.conf...58D
Altcode:
The solar activity (SA) evolution levels are not identical in the
northern and southern Sun's hemispheres. This fact was repeatedly
confirmed in the past by the analysis of a number of long-term
observations of various SA indices in individual atmospheric layers
of the Sun and in different bandwidths. The north-south asymmetry
(NSA) is thus a significant tool in investigation of long-term SA
variations. This paper presents a software tool to determine the
NSA of the area of bright chromospheric plages, as measured in the
Ca II K3 spectroheliograms registered since 1926 in the Observatário
Astronómico da Universidade de Coimbra, Portugal, as well as evolution
of sizes of these areas in the period 1996 - 2006. The algorithm
of the program is limited to determining the total area of bright
features in the Ca II K3 emission line based on the definition of the
threshold value for relative brightness and, therefore, it does not
resolve brightness of individual chromospheric features. A comparison
and cross-correlation of this NSA with the NSAs found for the sunspots
and coronal green line brightness have been added. In the near future
we intend to 1) determine the NSA of the area of bright chromospheric
Ca II K3 regions back to the year 1926, and 2) compare the evolution
of the surface area of these regions in the period 1970-2006 with the
evolution of the magnetic index obtained at Mt. Wilson Observatory,
which would also help in setting up a proxy reconstruction of the
magnetic index back to 1926. Since 2007 new spectroheliograms have been
recorded using a CCD camera and, therefore, in the future we will also
address this issue for the period 2007 - present.
Title: Slnečná aktivita a kozmické 'iarenie: magnetické pole
Slnka a úroveň kozmického žiarenia Title: Slnečná aktivita a
kozmické 'iarenie: magnetické pole Slnka a úroveň kozmického
žiarenia Title: Solar activity and cosmic radiation: Sun's magnetic
field and cosmic radiation levels.
Authors: Bodnárová, M.; Rybák, J.; Gömöry, P.; Kudela, K.
Bibcode: 2010nspm.conf..175B
Altcode:
In this work we have analyzed the correlation of the Sun's magnetic
activity and cosmic radiation levels during the period 1951-2004. As a
solar magnetic activity indicator, affecting the cosmic radiation, we
have chosen open magnetic field configurations which we characterized
by an open magnetic flux factor (OMFF). The OMFF was calculated from
the intensity measurements of the green coronal line. In calculations
leading to the relation between the OMFF and galactic cosmic radiation
(GCR) levels the cross-correlation of these datasets was used. The goal
of this contribution was to find mainly time-dependent changes in the
evolution of the OMFF and GCR correlation. In order to do so,besides
the correlation calculations based on the long time series of the
OMFF and GCR data covering the entire period 1951-2004 we have also
calculated the correlation of the OMFF and GCR data from shorter periods
(180 days). We have found that the cross-correlation evolution varies
depending on the phase of the solar cycle. During the minimum the
evolution is characterized by conspicuous periodicity with a period
~ 14 days and the cross-correlation function takes statistically
significant values. During the maximum the period of the variations
is not clear and the cross-correlation function takes low values that
are not statistically significant.
Title: Multiwavelength Imaging and Spectroscopy of Chromospheric
Evaporation in an M-class Solar Flare
Authors: Veronig, A. M.; Rybák, J.; Gömöry, P.; Berkebile-Stoiser,
S.; Temmer, M.; Otruba, W.; Vršnak, B.; Pötzi, W.; Baumgartner, D.
Bibcode: 2010ApJ...719..655V
Altcode: 2010arXiv1007.0930V
We study spectroscopic observations of chromospheric evaporation mass
flows in comparison with the energy input by electron beams derived
from hard X-ray (HXR) data for the white-light M2.5 flare of 2006 July
6. The event was captured in high-cadence spectroscopic observing mode
by SOHO/CDS combined with high-cadence imaging at various wavelengths
in the visible, extreme ultraviolet, and X-ray domain during the joint
observing campaign JOP171. During the flare peak, we observe downflows
in the He I and O V lines formed in the chromosphere and transition
region, respectively, and simultaneous upflows in the hot coronal
Si XII line. The energy deposition rate by electron beams derived
from RHESSI HXR observations is suggestive of explosive chromospheric
evaporation, consistent with the observed plasma motions. However, for
a later distinct X-ray burst, where the site of the strongest energy
deposition is exactly located on the Coronal Diagnostics Spectrometer
(CDS) slit, the situation is intriguing. The O V transition region
line spectra show the evolution of double components, indicative of
the superposition of a stationary plasma volume and upflowing plasma
elements with high velocities (up to 280 km s-1) in single
CDS pixels on the flare ribbon. However, the energy input by electrons
during this period is too small to drive explosive chromospheric
evaporation. These unexpected findings indicate that the flaring
transition region is much more dynamic, complex, and fine structured
than is captured in single-loop hydrodynamic simulations.
Title: Radio spectra generated during coalescence processes of
plasmoids in a flare current sheet
Authors: Karlický, M.; Bárta, M.; Rybák, J.
Bibcode: 2010A&A...514A..28K
Altcode:
Aims: Motivated by observations of the drifting pulsating
structures (DPSs) in solar radio spectra, we study the electromagnetic
(radio) emission generated during tearing and coalescence processes in a
flare current sheet.
Methods: For numerical simulations, we used
a 2.5-D particle-in-cell electromagnetic relativistic code. Numerical
data were analyzed by the wavelet methods.
Results: It is found
that the electromagnetic emission is generated during a coalescence of
plasmoids, and it has a quasi-periodic character. Detailed analysis
reveals that the electromagnetic emission is produced around the
interacting plasmoids just before their coalescence into a larger
one. The period in variations of electromagnetic emission corresponds
to that of magnetic field at the same region. Reflections of the
electromagnetic waves between interacting plasmoids are recognized. The
computed and observed periodicities are discussed. The similarity of
the DPSs with some radio bursts observed during star flares indicates
a broader applicability for this model.
Title: The SECIS instrument on the Lomnický Peak Observatory
Authors: Ambróz, J.; Radziszewski, K.; Rudawy, P.; Rybák, J.;
Phillips, K. J. H.
Bibcode: 2010CoSka..40....5A
Altcode: 2010arXiv1004.3454A
Heating mechanisms of the solar corona will be investigated at the high-altitude solar observatory Lomnicky Peak of the Astronomical
Institute of SAS (Slovakia) using its mid-size Lyot coronagraph
and post-focal instrument SECIS provided by Astronomical Institute
of the University of Wrocław (Poland). The data will be studied
with respect to the energy transport and release responsible
for heating the solar corona to temperatures of mega-Kelvins. In
particular investigations will be focused on detection of possible
high-frequency MHD waves in the solar corona. The scientific
background of the project, technical details of the SECIS system modified specially for the Lomnicky Peak coronagraph, and inspection
of the test data are described in the paper.
Title: Manifestations of the North - South Asymmetry in the
Photosphere and in the Green Line Corona
Authors: Sýkora, J.; Rybák, J.
Bibcode: 2010SoPh..261..321S
Altcode:
The north - south asymmetries (NSA) of three solar activity indices
are derived and mutually compared over a period of more than five solar
cycles (1945 - 2001). A catalogue of the hemispheric sunspot numbers,
the data set of the coronal green line brightness developed by us,
and the magnetic flux derived from the NSO/KP data (1975 - 2001)
are treated separately within the discrete low- and mid-latitude
zones (5° - 30°, 35° - 60°). The calculated autocorrelations,
cross-correlations, and regressions between the long-term NSA data
sets reveal regularities in the solar activity phenomenon. Namely, the
appearance of a distinct quasi-biennial oscillation (QBO) is evident
in all selected activity indices. Nevertheless, a smooth behavior of
QBO is derived only when sufficient temporal averaging is performed
over solar cycles. The variation in the significance and periodicity of
QBO allows us to conclude that the QBO is not persistent over the whole
solar cycle. A similarity in the photospheric and coronal manifestations
of the NSA implies that their mutual relation will also show the QBO. A
roughly two-year periodicity is actually obtained, but again only after
significant averaging over solar cycles. The derived cross-correlations
are in fact variable in degree of correlation as well as in changing
periodicity. A clear and significant temporal shift of 1 - 2 months
in the coronal manifestation of the magnetic flux asymmetry relative
to the photospheric manifestation is revealed as a main property of
their mutual correlation. This shift can be explained by the delayed
large-scale coronal manifestation in responding to the emergence of
the magnetic flux in the photosphere. The reliability of the derived
results was confirmed by numerical tests performed by selecting
different numerical values of the used parameters.
Title: Magnetic loop emergence within a granule
Authors: Gömöry, P.; Beck, C.; Balthasar, H.; Rybák, J.; Kučera,
A.; Koza, J.; Wöhl, H.
Bibcode: 2010A&A...511A..14G
Altcode: 2009arXiv0910.4449G
Aims: We investigate the temporal evolution of magnetic
flux emerging within a granule in the quiet-Sun internetwork at
disk center.
Methods: We combined IR spectropolarimetry of
high angular resolution performed in two Fe i lines at 1565 nm with
speckle-reconstructed G-band imaging. We determined the magnetic
field parameters by a LTE inversion of the full Stokes vector using
the SIR code, and followed their evolution in time. To interpret
the observations, we created a geometrical model of a rising loop in
3D. The relevant parameters of the loop were matched to the observations
where possible. We then synthesized spectra from the 3D model for a
comparison to the observations.
Results: We found signatures of
magnetic flux emergence within a growing granule. In the early phases,
a horizontal magnetic field with a distinct linear polarization signal
dominated the emerging flux. Later on, two patches of opposite circular
polarization signal appeared symmetrically on either side of the linear
polarization patch, indicating a small loop-like structure. The mean
magnetic flux density of this loop was roughly 450 G, with a total
magnetic flux of around 3 × 1017 Mx. During the ~12 min
episode of loop occurrence, the spatial extent of the loop increased
from about 1 to 2 arcsec. The middle part of the appearing feature
was blueshifted during its occurrence, supporting the scenario of an
emerging loop. There is also clear evidence for the interaction of
one loop footpoint with a preexisting magnetic structure of opposite
polarity. The temporal evolution of the observed spectra is reproduced
to first order by the spectra derived from the geometrical model. During
the phase of clearest visibility of the loop in the observations,
the observed and synthetic spectra match quantitatively.
Conclusions: The observed event can be explained as a case of flux
emergence in the shape of a small-scale loop. The fast disappearance
of the loop at the end could possibly be due to magnetic reconnection.
Title: Dynamics of isolated magnetic bright points derived from
Hinode/SOT G-band observations
Authors: Utz, D.; Hanslmeier, A.; Muller, R.; Veronig, A.; Rybák,
J.; Muthsam, H.
Bibcode: 2010A&A...511A..39U
Altcode: 2009arXiv0912.1965U
Context. Small-scale magnetic fields in the solar photosphere can
be identified in high-resolution magnetograms or in the G-band as
magnetic bright points (MBPs). Rapid motions of these fields can
cause magneto-hydrodynamical waves and can also lead to nanoflares by
magnetic field braiding and twisting. The MBP velocity distribution is
a crucial parameter for estimating the amplitudes of those waves and
the amount of energy they can contribute to coronal heating.
Aims: The velocity and lifetime distributions of MBPs are derived from
solar G-band images of a quiet sun region acquired by the Hinode/SOT
instrument with different temporal and spatial sampling rates.
Methods: We developed an automatic segmentation, identification
and tracking algorithm to analyse G-Band image sequences to obtain
the lifetime and velocity distributions of MBPs. The influence of
temporal/spatial sampling rates on these distributions is studied and
used to correct the obtained lifetimes and velocity distributions for
these digitalisation effects.
Results: After the correction of
algorithm effects, we obtained a mean MBP lifetime of (2.50 ± 0.05)
min and mean MBP velocities, depending on smoothing processes, in
the range of (1-2) km~s-1. Corrected for temporal sampling
effects, we obtained for the effective velocity distribution a Rayleigh
function with a coefficient of (1.62 ± 0.05) km~s-1. The
x- and y-components of the velocity distributions are Gaussians. The
lifetime distribution can be fitted by an exponential function.
Title: G-band to Blue-Continuum Excess as quasi total field strength
magnetogram
Authors: Utz, D.; Hanslmeier, A.; Veronig, A.; Rybák, J.; Muller,
R.; Muthsam, H.
Bibcode: 2010CEAB...34...13U
Altcode:
The dynamics of the solar plasma is driven by strong localized magnetic
fields. It is well known that activity like flares and CMEs are related
to the dissipation and reconnection of these magnetic fields. These
energetic releases influence and make up the so called space weather. It
is therefore of vital importance to get a deeper understanding of the
magnetic fields of the Sun. To get this insights, it is crucial to
obtain information on the magnetic fields with spatial and temporal
resolutions as high as possible. In this paper we outline an easy to
apply method to obtain quasi total magnetic field strength magnetograms
out of two simple filtergrams (blue continuum and G-band). We will
present our simple approach and the first results of this method and
give finally an outlook what has to be done in the future.
Title: Dynamics of G-band bright points derived using two fully
automated algorithms
Authors: Bodnárová, M.; Utz, D.; Rybák, J.; Hanslmeier, A.
Bibcode: 2010CEAB...34...25B
Altcode:
Small-scale magnetic field concentrations (∼ 1 kG) in the solar
photosphere can be identified in the G-band of the solar spectrum
as bright points. Study of the G-band bright points (GBPs) dynamics
can help us in solving several questions related also to the coronal
heating problem. Here a set of 142 G-band speckled images obtained
using the Dutch Open Telescope (DOT) on October 19, 2005 are used to
compare identification of the GBPs by two different fully automated
identification algorithms: an algorithm developed by Utz et al. (2009a,
2009b) and an algorithm developed according to papers of Berger et
al. (1995, 1998). Temporal and spatial tracking of the GBPs identified
by both algorithms was performed resulting in distributions of
lifetimes, sizes and velocities of the GBPs. The obtained results show
that both algorithms give very similar values in the case of lifetime
and velocity estimation of the GBPs, but they differ significantly
in case of estimation of the GBPs sizes. This difference is caused
by the fact that we have applied no additional exclusive criteria on
the GBPs identified by the algorithm based on the work of Berger et
al. (1995, 1998). Therefore we conclude that in a future study of the
GBPs dynamics we will prefer to use the Utz's algorithm to perform
identification and tracking of the GBPs in G-band images.
Title: Multi-wavelength fine structure and mass flows in solar
microflares
Authors: Berkebile-Stoiser, S.; Gömöry, P.; Veronig, A. M.; Rybák,
J.; Sütterlin, P.
Bibcode: 2009A&A...505..811B
Altcode:
Aims: We study the multi-wavelength characteristics at high spatial
resolution, as well as chromospheric evaporation signatures of solar
microflares. To this end, we analyze the fine structure and mass
flow dynamics in the chromosphere, transition region and corona of
three homologous microflares (GOES class <A9/0.7 with/without
background), which occurred on July 4, 2006 in AR 10898.
Methods: A multi-wavelength analysis using temporally and spatially
highly resolved imaging data from the Dutch open telescope (Hα,
Ca ii H), the transition region and coronal explorer (17.1 nm),
the extreme-ultraviolet imaging telescope (19.5 nm), and the Reuven
Ramaty high energy solar spectroscopic imager (≳3 keV) was carried
out. EUV line spectra provided by the coronal diagnostic spectrometer
are searched for Doppler shifts in order to study associated
plasma flows at chromospheric (He i, T∼3.9× 104 K),
transition region (e.g. O v, T∼ 2.6× 105 K), and
coronal temperatures (Si xii, T∼ 2× 106 K). RHESSI
X-ray spectra provide information about non-thermal electrons.
Results: The multi-wavelength appearance of the microflares is in
basic agreement with the characteristics of large flares. For the
first event, a complex flare sequence is observed in TRACE 17.1 nm
images (T≈ 1 MK), which show several brightenings, narrow loops
of enhanced emission, and an EUV jet. EIT 19.5 nm data (T≈ 1.5 MK)
exhibit similar features for the third event. DOT measurements show
finely structured chromospheric flare brightenings for all three events,
loop-shaped fibrils of increased emission between Hα brightenings, as
well as a similar feature in Ca ii. For all three events, a RHESSI X-ray
source (3-8 keV, T ≳ 10 MK) is located in between two chromospheric
brightenings situated in magnetic flux of opposite polarity. We find
the flow dynamics associated with the events to be very complex. In
the chromosphere and transition region, CDS observed downflows for
the first (v ≲ 40 km s-1), and upflows for the second
event (v ≲ 40 km s-1). During the third microflare, we
find upflows of ≲ 20 km s-1 and also weak downflows of
≲20 km s-1 in two separate brightenings. For all three
microflares, multi-component fitting is needed for several profiles
of He i, O v, and Ne vi lines observed at the flare peaks, which
indicate spatially unresolved, oppositely directed flows of ≲180
km s-1. We interpret these flows as twisting motions of
the flare loops. Loop-shaped fibrils in between Hα brightenings
showing opposite flow directions (v≈5 km s-1) are also
observed in DOT Hα Dopplergrams. RHESSI X-ray spectra show evidence
of non-thermal bremsstrahlung for two of the three microflares. The
electron beam flux density deposited in the chromosphere for these
events is estimated to straddle the threshold heating flux between
gentle and explosive evaporation. Appendix A and the movie are
only available in electronic form at http://www.aanda.org
Title: ``Drifting tadpoles'' in wavelet spectra of decimetric radio
emission of fiber bursts
Authors: Mészárosová, H.; Karlický, M.; Rybák, J.; Jiřička, K.
Bibcode: 2009A&A...502L..13M
Altcode:
Aims: The solar decimetric radio emission of fiber bursts was
investigated searching for the “drifting tadpole” structures
proposed by theoretical studies.
Methods: Characteristic periods
with the tadpole pattern were searched for in the radio flux time
series by wavelet analysis methods.
Results: For the first time,
we have found drifting tadpoles in the wavelet spectra of the decimetric
radio emission associated with the fiber bursts observed in July 11,
2005. These tadpoles were detected at all radio frequencies in the
1602-1780 MHz frequency range. The characteristic period of the wavelet
tadpole patterns was found to be 81.4 s and the frequency drift of the
tadpole heads is -6.8 MHz s-1. These tadpoles are interpreted
as a signature of the magnetoacoustic wave train moving along a dense
flare waveguide and their frequency drift as a motion of the wave
train modulating the radio emission produced by the plasma emission
mechanism. Using the Aschwanden density model of the solar atmosphere,
only low values of the Alfvén speed and the magnetic field strength
in the loop guiding this wave train were derived which indicates a
neutral current sheet as the guiding structure. The present analysis
supports the model of fiber bursts based on whistler waves.
Title: Analyses of magnetic field structures for active region 10720
using a data-driven 3D MHD model
Authors: Wu, S. T.; Wang, A. H.; Gary, G. Allen; Kucera, Ales; Rybak,
Jan; Liu, Yang; Vrśnak, Bojan; Yurchyshyn, Vasyl
Bibcode: 2009AdSpR..44...46W
Altcode:
In order to understand solar eruptive events (flares and CMEs) we
need to investigate the changes at the solar surface. Thus, we use
a data-driven, three-dimensional magnetohydrodynamic (MHD) model to
analyze a flare and coronal mass ejection productive active region,
AR 10720 on January 15, 2005. The measured magnetic field from Big
Bear Solar Observatory (BBSO) digital vector magnetograph (DGVM) was
used to model the non-potential coronal magnetic field changes and the
evolution of electric current before and after the event occurred. The
numerical results include the change of magnetic flux ( Φ), the net
electric current ( IN), the length of magnetic shear of the
main neutral line ( Lss), the flux normalized measure of
the field twist (α={μIN}/{Φ}) with μ being the magnetic
permeability. The current helicity ( Hc) injected into the
corona and the photospheric surface velocity are also computed. The
characteristic parameters of the buildup process before the event and
the decay process after the event are investigated and the amount of
magnetic energy converted to drive the event is estimated.
Title: Tadpoles in Wavelet Spectra of a Solar Decimetric Radio Burst
Authors: Mészárosová, H.; Karlický, M.; Rybák, J.; Jiřička, K.
Bibcode: 2009ApJ...697L.108M
Altcode:
In the solar decimetric type IV radio event observed on 2001 June 13,
we have found wavelet tadpole patterns for the first time. They were
detected simultaneously at all radio frequencies in the 1.1-4.5 GHz
frequency range. The characteristic period of the wavelet tadpole
patterns was found to be 70.9 s. The parameters of the tadpoles on
different frequencies are very similar and the correlations between
individual radio fluxes are high. These tadpoles are interpreted as a
signature of the magnetoacoustic wave train moving along the flare loop
through the radio source and modulating its gyrosynchrotron emission.
Title: Coronal fast wave trains of the decimetric type IV radio
event observed during the decay phase of the June 6, 2000 flare
Authors: Mészárosová, H.; Sawant, H. S.; Cecatto, J. R.; Rybák, J.;
Karlický, M.; Fernandes, F. C. R.; de Andrade, M. C.; Jiřička, K.
Bibcode: 2009AdSpR..43.1479M
Altcode:
The 22 min long decimetric type IV radio event observed during the
decay phase of the June 6, 2000 flare simultaneously by the Brazilian
Solar Spectroscope (BSS) and the Ondřejov radiospectrograph in
frequency range 1200-4500 MHz has been analyzed. We have found that
the characteristic periods of about 60 s belong to the long-period
spectral component of the fast wave trains with a tadpole pattern
in their wavelet power spectra. We have detected these trains in
the whole frequency range 1200-4500 MHz. The behavior of individual
wave trains at lower frequencies is different from that at higher
frequencies. These individual wave trains have some common as well as
different properties. In this paper, we focus on two examples of wave
trains in a loop segment and the main statistical parameters in their
wavelet power and global spectra are studied and discussed.
Title: Observations of Chromospheric Evaporation Flows in RHESSI
Microflares
Authors: Berkebile-Stoiser, S.; Gömöry, P.; Veronig, A.; Rybák, J.
Bibcode: 2009CEAB...33..169B
Altcode:
We present the analysis of two homologous microflares of GOES class
A9 with respect to mass flows in the chromosphere and transition
region. Both events show non-thermal emission (evidence for beamed
electrons) in RHESSI X-ray spectra. As outlined by observations of
the Coronal Diagnostic Spectrometer, we find for the first event
downflows in the He I, O V and Ne VI line reaching speeds up to 40
km s^{-1} at the position of chromospheric flare brightenings. On
the other hand, upflows with velocities ≲40 km^{-1} are observed
for the second microflare. According to hydrodynamic flare
simulations, the non-thermal electron energy density F deposited in
the chromosphere determines if chromospheric evaporation is `gentle' or
`explosive'. Thus, we derive rough estimates for F in our microflares
and compare the results to the observed CDS flow properties.
Title: Multi-wavelength Observations of Microflares Near an Active
Region
Authors: Bein, B.; Veronig, A.; Rybak, J.; Gömöry, P.;
Berkebile-Stoiser, S.; Sütterlin, P.
Bibcode: 2009CEAB...33..179B
Altcode:
We study the multi-wavelength characteristics of a microflaring active
region (AR 10898) near disc centre. The analysed data were from the
4^{th} of July 2006, and were recorded by DOT (Hα, Ca II H), RHESSI
(X-rays), TRACE (EUV) and SOHO/MDI (magnetograms). The identified
microflare events were studied with respect to their magnetic field
configuration and their multi-wavelength time evolution.
Title: Solar Convection and Oscillation Interaction
Authors: Hanslmeier, A.; Kučera, A.; Rybák, J.; Wöhl, H.;
Gömöry, P.
Bibcode: 2009CEAB...33...51H
Altcode:
In this paper we investigate bisectors of solar photospheric lines. The
bisectors reflect vertical velocity gradients over the height of line
formation and therefore reveal important information about the dynamics
in these layers. Their shape and shift is influenced by (a) convective
motions, (b) oscillatory motions that can act differently at different
photospheric heights. The bisectors are selected from different
locations that show mainly a granular evolution or an intergranular
evolution. Two selection criteria were applied: continuum intensity
(enhanced for granular bisectors, reduced for intergranular bisectors),
and full width at half maximum values (enhanced for intergranular
bisectors). The results demonstrate how oscillatory motions influence
the bisectors as a whole. In the example given a smaller amplitude of
oscillations over intergranular areas is indicated.
Title: Observational Evidence for Shocks in the Solar Photosphere -
New TESOS/VTT Results
Authors: Rybak, J.; Kucera, A.; Hanslmeier, A.; Woehl, H.;
Wedemeyer-Boehm, S.; Steiner, O.
Bibcode: 2008ESPM...12.2.36R
Altcode:
High-resolution spectroscopic observations recently acquired with the
TESOS spectrometer at the Vacuum Tower Telescope (VTT, Observatorio
del Teide, Tenerife) are used to test predictions regarding strongly
dynamic events in the photosphere as obtained from three-dimensional
numerical simulations with the CO5BOLD-code. Time series of
two-dimensional maps of the Fe I 543.4 nm spectral line profile at
different centre-to-limb positions are investigated in a statistical
sense by comparing the distributions of individual spectral parameters
derived from observations with the corresponding distributions
from synthesized spectra calculated with the LINFOR3D code from
the simulations. Appropriate degradation of the synthesized spectra
was applied in order to take the limited spatial resolution of the
telescope, seeing effects, and the scattered instrumental light into
account. At the actual spatial resolution of 0.5 arc sec, the
statistics show that signatures of the photospheric dynamics, including
the most dynamical events like occasional supersonic flows of plasma in
the nearly horizontal direction, are very similar in both observations
and simulations. Discrepancies are found only for those spectral
parameters (residual line intensity, Doppler line core shifts), which
are affected by non-LTE effects, since non-LTE effects are not taken
into account in the synthesis of the Fe I 543.4nm spectral line.
Title: Flare Generated Coronal Fast Wave Trains of Decimetric Radio
Pulsations
Authors: Meszarosova, H.; Sawant, H. S.; Cecatto, J. R.; Rybak, J.;
Karlicky, M.; Fernandes, F. C. R.; Jiricka, K.; Andrade, M. C.
Bibcode: 2008ESPM...122.105M
Altcode:
The 22 minutes lasting interval of broadband dm-radio pulsations
observed simultaneously during a decay phase of the June 6, 2000 flare
by the Brazilian Solar Spectroscope (BSS) and Ondrejov radiospectrograph
in frequency range 1200-4500 MHz has been analyzed. We have realized
that dominant periods (32-64 s) belong to fast wave trains with a
tadpole pattern in their wavelet power spectra. The whole time interval
contains series of about 4 wave trains. These trains propagate in
whole frequency range 1200-4500 MHz. The propagation of individual
trains at lower levels of the solar atmosphere (higher frequencies) is
different from propagation of individual trains at higher ones (lower
frequencies). The wave trains at the same frequencies but in different
time subintervals have some common as well as different properties. The
main statistical parameters (periodical, quasi-periodical and decay
phase) of these wave trains in their wavelet power spectra have been
studied and the first results will be presented and discussed.
Title: Multi-wavelength Observations of Dynamic Fibrils in the Upper
Photosphere and Chromosphere
Authors: Kucera, A.; Beck, Ch.; Gomory, P.; Koza, J.; Woehl, H.;
Rybak, J.
Bibcode: 2008ESPM...12.2.52K
Altcode:
Spatial and temporal evolution of dynamic fibrils (DF) as well as
coupling with photospheric features was investigated. The
main target were remnants in the active region 10997 on May 28,
2008. We used about 1 hour series of multi wavelength simultaneous
observations of the DFs and corresponding photospheric features. The
observations were performed with the german Vacuum Tower Telescope
equipped with several post-focus instruments. Namely: TESOS (Triple
Etalon SOlar Spectrometer) instrument was used in polarimetric mode
(VIP=Visual Imaging Polarimeter) to register 2D spectra of the DFs in
H-alpha line and in magnetically sensitive Fe I 630.2 nm line. TIP
(Tenerife Infrared Polarimeter) mounted on the Echelle spectrograph
was used for spectropolarimetric observations of two neutral iron
lines at 1.56 micrometers. We scanned 2D area 80" x 5", producing
thus 2D maps of intensity, velocity and magnetic field of the low
photosphere under the chromospheric fibril field. Additionally
G-band and H-alpha images were registered with high cadence and
the supporting data from the TRACE satellite (17.1 nm, WL, Lyman
alpha line and 160 nm continuum) are also available. After careful
spatial coalignment of 2D maps we first selected numerous DFs in the
H-alpha images. Then we investigated temporal evolution of those DFs
concerning changes of their dimensions, positions and fluctuations
and correlated these characteristics with temporal evolution of the
intensities, velocities and magnetic field characteristics observed in
the spatially corresponding photosphere. The poster demonstrates the
complex observations, data reduction and coalignment and preliminary
results on coupling between DFs and underlying photospheric features.
Title: Observation of Turbulence in Solar Surface Convection:
I. Line Parameter Correlations
Authors: Hanslmeier, A.; Kučera, A.; Rybák, J.; Wöhl, H.
Bibcode: 2008SoPh..249..293H
Altcode: 2008SoPh..tmp...88H
By using slit observations of solar photospheric lines shifted by 0.4
arcsec, a 2D field on the Sun was scanned to obtain a 16-minute time
series of 2D line-parameter variations. The aim was to investigate in
detail the occurrence of turbulence that can be measured by line-width
variations extracted from the line profiles. The continuum-intensity
variation served as a proxy for granular (bright) and intergranular
(dark) areas. The results show that turbulence is not limited to
the intergranular space but is also produced by horizontal motions
that may become supersonic, leading to turbulence. These motions
lead to brightenings, as predicted by theoretical models. Thus,
enhanced line-width variations are found to occur in both bright and
dark areas. A Sobel filter served to detect the areas where strong
gradients in the line parameters occur. By applying this filter to the
different line-parameter variations over the 2D field observed, we can
determine whether there exists a similarity of these strong-gradient
patterns with other parameters that characterize granular motions such
as intensity variations or velocity fluctuations.
Title: Acceleration in Fast Halo CMEs and Synchronized Flare HXR
Bursts
Authors: Temmer, M.; Veronig, A. M.; Vršnak, B.; Rybák, J.; Gömöry,
P.; Stoiser, S.; Maričić, D.
Bibcode: 2008ApJ...673L..95T
Altcode:
We study two well-observed, fast halo CMEs, covering the full CME
kinematics including the initiation and impulsive acceleration phase,
and their associated flares. We find a close synchronization between the
CME acceleration profile and the flare energy release as indicated by
the RHESSI hard X-ray flux onsets, as well as peaks occur simultaneously
within 5 minutes. These findings indicate a close physical connection
between both phenomena and are interpreted in terms of a feedback
relationship between the CME dynamics and the reconnection process in
the current sheet beneath the CME.
Title: Period variations of radio pulsations observed during decay
phase of the June 06, 2000 flare
Authors: Sawant, Hanumant; Meszarosova, Hana; Cecatto, José;
Karlicky, Marian; Rybak, Jan; Fernandes, Francisco; Andrade, Maria;
Jiricka, Karel
Bibcode: 2008cosp...37.2758S
Altcode: 2008cosp.meet.2758S
The 22 minutes lasting interval of broadband dm-radio pulsations
observed during decay phase of the June 6, 2000 flare by Brazilian
Solar Spectroscope (BSS) and Ondrejov radiospectrograph in frequency
range 1200-4500 MHz have been analyzed for its complex temporal
variability. To understand the global relationship between radio
fluxes on lower and higher frequencies and to recognize different
emission mechanisms, we have made the cross-correlation of the radio
fluxes at different frequencies during time intervals under study. We
have realized that the dominant periods are not spread during whole
22 minutes time interval but their appearance is concentrated into 7
shorter time subintervals that we have then studied in detail. These
subintervals last 9-33 s, on average 21 s. The pulsations inside the
subintervals usually have higher intensity than the other ones and
characteristic dominant periods of these quasi-regular pulsations are
0.5-78.8 s. We were interested in possible differences among dominant
periods of individual time intervals as well as between the periods
at frequencies below and above 2000 MHz. Periods > 60 s are rather
rare. The periods < 40 s occur more frequently at frequencies below
2000 MHz than at frequencies above 2000 MHz. Occurrence of the periods
> 40 s is similar at frequencies below and above 2000 MHz. Results
are compared with TRACE and EIT/SOHO images and discussed in framework
of multi-scaling flare loop interactions.
Title: North-South Asymmetry of Ca II K Plages
Authors: Dorotovič, I.; Journoud, P.; Rybák, J.; Sýkora, J.
Bibcode: 2007ASPC..368..527D
Altcode:
The level and evolution of solar activity is not identical in the
northern and southern Sun's hemispheres. This fact was repeatedly
confirmed in the past by analysis of a number of long-term observations
of various solar activity indices. Presently, it seems that the
north-south (N-S) asymmetry represents quite specific, independent
and very promising tool to advance in analysis of the long-term solar
activity variations. This paper is focused to give a software tool for
estimation of the N-S asymmetry in the area of bright chromospheric
plages, as measured on the Ca II K3 spectroheliograms
registered since 1926 in the Observatório Astronómico da Universidade
de Coimbra, Portugal. In fact, studies of the N-S asymmetry of just
this phenomenon are rare, namely due to absence of technique allowing
reliable quantitative estimations of the Ca II K3 plages
parameters. Our algorithm is also partially limited, it provides the
area of bright Ca II K3 emission structures, but it does
not perceive differences in the brightness of individual chromospheric
features. As for the N-S asymmetry of the chromospheric plages alone,
we present here a sample of its estimation only. Its behavior during
the first half of 2000 year is provided to illustrate application of
the software developed. A comparison and cross-correlation with the N-S
asymmetries found for the sunspots and corona green line brightness is
added. We intend to discuss the results of more extensive analysis of
the chromospheric plages N-S asymmetry as soon as a sufficiently long
time series of the Ca II K3 Coimbra spectroheliograms will
be digitized and processed.
Title: Temporal Variations in Fibril Orientation
Authors: Koza, J.; Sütterlin, P.; Kučera, A.; Rybák, J.
Bibcode: 2007ASPC..368..115K
Altcode: 2007astro.ph..3733K
We measure variations in orientation of fourteen dynamic fibrils as
a function of time in a small isolated plage and nearby network using
a 10-min time sequence of Hα filtergrams obtained by the Dutch Open
Telescope. We found motions with average angular velocities of the
order of 1 deg min-1 suggesting systematic turning from
one limit position to another, particularly apparent in the case of
fibrils with lifetimes of a few minutes. Shorter fibrils tend to turn
faster than longer ones, which we interpret as due to vortex flows in
the underlying granulation that twist magnetic fields.
Title: Propagating Waves in the Chromospheric Network
Authors: Gömöry, P.; Rybák, J.; Kučera, A.; Curdt, W.; Wöhl, H.
Bibcode: 2007ASPC..368..133G
Altcode:
Wave modulation of ultraviolet emissions originated in and above quiet
chromospheric network is studied. In particular, cross-correlation,
wavelet analysis and phase difference analysis of the intensities
as well as the Doppler shifts of emission lines of He I 584.33 Å
(chromosphere), O V 629.73 Å (transition region) and Mg IX 368.07 Å
(corona) are employed to study waves at different heights and their
direction of propagation. The results are interpreted as evidence of
compressive waves that propagate downward from the transition region
to the chromosphere in the observed chromospheric network. Different
scenarios regarding the origin and source localization of these waves
are discussed.
Title: The height dependence of temperature velocity correlation in
the solar photosphere
Authors: Koza, J.; Kučera, A.; Rybák, J.; Wöhl, H.
Bibcode: 2007msfa.conf..139K
Altcode: 2007arXiv0704.0603K
We derive correlation coefficients between temperature and line-of-sight
velocity as a function of optical depth throughout the solar photosphere
for the non-magnetic photosphere and a small area of enhanced magnetic
activity. The maximum anticorrelation of about -0.6 between temperature
and line-of-sight velocity in the non-magnetic photosphere occurs at
log [tau] 5 = -0.4. The magnetic field is another decorrelating factor
along with 5-min oscillations and seeing.
Title: Spectral Characteristics of the Photosphere near a Flare
Authors: Kučera, A.; Wöhl, H.; Rybák, J.; Wu, S. T.; Wang, A. H.
Bibcode: 2007CEAB...31...21K
Altcode:
We present the temporal evolution of dynamical characteristics of the
solar photosphere in an active region near a flare. Namely, spatial
and temporal variations of Doppler velocities at different heights in
the photosphere mapped by eight photospheric lines are presented for
a time span of 45 minutes. The dynamics of the photosphere before and
during a flare which occurred nearby is discussed. We found that
downward plasma motions are well pronounced up to 300 km height in the
photosphere but did not reach deeper layers. The downward velocities of
the plasma motion caused by the flare are about 1.2 km/s and they are
channelled in a thin structure - flux-tube with diameter less than 0.8
arcseconds. The velocities are better noticeable in the active parts
of the target than in the quiet ones. The magnetic configuration of
the active region is compared with the dynamics behaviour.
Title: The Height Dependence of Quiet-Sun Photospheric Temperature
Fluctuations in Observations and Simulations
Authors: Koza, J.; Kučera, A.; Rybák, J.; Wöhl, H.
Bibcode: 2006ASPC..354...43K
Altcode:
We derive rms temperature fluctuations as a function of height
throughout the solar photosphere for the non-magnetic photosphere and
a small area of enhanced magnetic activity, through semi-empirical
inversion based on response functions of a 15-minute time sequence
of 118 arcsec-long slit spectrograms taken at disk center. While the
observed low photosphere shows small temperature fluctuations (about
≈ 50 K), the sub-photospheric layers and the upper photosphere
show larger fluctuations, with similar gradients as in 3-D radiation
discretionary-hydrodynamics simulations. However, the observed rms
temperature fluctuations are lower than in the simulations at all
depths, which we attribute to smearing by atmospheric seeing.
Title: Long period variations of dm-radio and X-ray fluxes in three
X-class flares
Authors: Mészárosová, H.; Karlický, M.; Rybák, J.; Fárník,
F.; Jiřička, K.
Bibcode: 2006A&A...460..865M
Altcode:
Aims.Long period (≥60 s) variations of the radio (0.8-4.5 GHz) and
X-ray fluxes observed during the July 14, 2000, April 12, 2001, and
April 15, 2001 flares by the Ondřejov radiospectrograph and Yohkoh
spacecraft are studied by statistical methods.
Methods: .In
the flares under study, characteristic periods are searched for by the
Fourier and wavelet methods. To understand the origin of the 0.8-4.5 GHz
drifting burst with long period variations, observed at the beginning of
the April 15, 2001 flare, cross-correlations, time shifts, coherence,
and phase differences in its time series are computed.
Results:
.The global statistical study of these flares revealed characteristic
periods in the interval of 60-513 s in the radio (0.8-4.5 GHz) and
60-330 s in the X-ray Yohkoh fluxes. Cross-correlations between the
radio fluxes at different frequencies helped us to determine the bursts
generated by plasma or gyro-synchrotron mechanisms. In the April 12,
2001 flare, soft X-ray fluxes of the sources located at the loop-top
and footpoints of a flare loop vary with the period of 60-320 s, and
they are highly correlated. But their relation to the radio (1.1 GHz -
plasma emission and 4.0 GHz - gyro-synchrotron emission) is complex. At
the beginning of the April 15, 2001 flare, in the 0.8-4.5 GHz range,
a broadband drifting radio burst with the time variation of 61-320 s
was observed at times of flare loop ejection. Its detailed statistical
analysis shows that this burst consists of two parts, and, that first
part is generated by the plasma emission mechanism and the second,
probably, by the gyro-synchrotron one. The characteristic period of
about 300 s found in three X-class flares in their dm-radio and X-ray
emissions is discussed.
Title: A New Method for Comparing Numerical Simulations with
Spectroscopic Observations of the Solar Photosphere
Authors: Rybák, J.; Kučera, A.; Wöhl, H.; Wedemeyer-Böhm, S.;
Steiner, O.
Bibcode: 2006ASPC..354...77R
Altcode:
A method for comparing high-resolution spectroscopic observations of
the solar photosphere with numerical simulations of convection in the
solar photosphere is presented. It is based on the comparison of
the granular continuum contrast obtained from both the observations and
the synthetic spectra, when the latter are calculated from numerical
simulations using a particular type of data degradation. This method
can be used post facto when a minimum of auxiliary information on
characteristics of the telescope/spectrograph and on seeing conditions
is available. Here, the method is applied to results of numerical
simulations computed with the CO5BOLD code and high-resolution
spectroscopic observations obtained with the VTT on Tenerife.
Title: Photospheric modeling through spectral line
inversion. Temperature and radial velocity stratifications and
fluctuations
Authors: Koza, J.; Kučera, A.; Rybák, J.; Wöhl, H.
Bibcode: 2006A&A...458..941K
Altcode:
Aims.We aim to determine average radial stratifications of various
physical parameters throughout the solar photosphere at high angular
resolution for non-magnetic and magnetic areas and to compare these
with standard semiempirical 1D modeling and with 3D hydrodynamics (HD)
and magnetohydrodynamics (MHD) simulations.
Methods: .We analyse
a 15-min sequence of adaptive-optics spectrograms of very high angular
resolution taken at solar disk centre. We split the data between a
quiet area and a magnetic one and derive mean temperature and velocity
stratifications and fluctuations for these separately by applying
LTE inversion based on response functions.
Results: .The mean
temperature stratifications in the non-magnetic region agree well with
the classical 1D models and the 3D simulations at all heights. However,
the observed rms temperature is much lower than in the simulations,
the observed mean velocities indicate more upflows, and the observed
velocity fluctuations are smaller except in upper layers. Some of
the discrepancies are likely to result from remaining smearing by
atmospheric seeing and instrumental limitations. The magnetic area
shows conspicuous behaviour at large height. We also find evidence of
fast low-photosphere downflows in the magnetic area and of enhanced
temperature above a small pore.
Title: Periodicities in Irradiance and in other Solar Activity
Indices During Cycle 23
Authors: Ataç, T.; Özgüç, A.; Rybak, J.
Bibcode: 2006SoPh..237..433A
Altcode: 2006SoPh..tmp...21A
Magnetic fields give rise to distinctive features in different
solar atmospheric regimes. To study this, time variations of the
flare index, sunspot number and sunspot area, each index arising from
different physical conditions, were compared with the solar composite
irradiance throughout cycle 23. Rieger-type periodicities in these
time series were calculated using Fourier and wavelet transforms
(WTs). The peaks of the wavelet power of these periodicities appeared
between the years 1999 and 2002. We found that the solar irradiance
oscillations are less significant than those in the other indices
during this cycle. The irradiance shows non-periodic fluctuations
during this time interval. The peaks of the flare index, sunspot number
and sunspot total area were seen around 2000.4, 1999.9 and 2001.0,
respectively. These periodicities appeared intermittently and were
not simultaneous in different solar activity indices during the three
years of the maximum phase of solar cycle 23.
Title: Response of the Coronal N-S Asymmetry to its Manifestations
in the Photosphere
Authors: Rybak, J.; Sykora, J.
Bibcode: 2006IAUJD...8E..22R
Altcode:
The North-South (N-S) asymmetries of three solar activity indices
are mutually compared over the period of more than five solar cycles
(1945 - 2001). Our own catalogue of the hemispheric sunspot numbers,
the database of the uniform coronal green line brightness and the
magnetic field strength, as derived from the NSO/KP data (1975-2001),
are treated within the discrete latitudinal zones (5° - 30° and 35°
- 60°). The calculated paired correlations and regressions reveal
much better expressed mutual relations between the N-S asymmetries
than those are manifested if using the indices alone. A distinctly
different behaviour of the N-S asymmetries found at different solar
cycle phases separately for the low- and mid-latitude zones is picked
out. The revealed differences could be considered when any dynamo
theories of solar activity are developed.
Title: Study of a Small-Scale Eruptive Event Observed by SOHO/SUMER
Authors: Tomasz, F.; Régnier, S.; Schwarz, P.; Rybák, J.; Kucera,
A.; Heinzel, P.; Curdt, W.; Wöhl
Bibcode: 2006ESASP.617E..79T
Altcode: 2006soho...17E..79T
No abstract at ADS
Title: Multi-Wavelength Observations with High Resolution of a M5.4
Flare from Ground and Space
Authors: Kucera, A.; Wöhl, H.; Rybák, J.; Gömöry, P.; Veronig, A.
Bibcode: 2006ESASP.617E..68K
Altcode: 2006soho...17E..68K
No abstract at ADS
Title: The Dynamics and Structure of the Solar Atmosphere As Obtained
from Combined SUMER/SOHO and TIP2/VTT Observations
Authors: Tomasz, F.; Régnier, S.; Schwartz, P.; Rybák, J.; Kucera,
A.; Heinzel, P.; Curdt, W.; Wöhl
Bibcode: 2006ESASP.617E..78T
Altcode: 2006soho...17E..78T
No abstract at ADS
Title: SOHO/CDS observations of waves above the network
Authors: Gömöry, P.; Rybák, J.; Kučera, A.; Curdt, W.; Wöhl, H.
Bibcode: 2006A&A...448.1169G
Altcode:
We analyze temporal variations in the intensities and the Doppler shifts
of He i 584.33 Å (chromosphere), O v 629.73 Å (transition region),
and Mg ix 368.07 Å (corona) measured in and above chromospheric
network near disk center with the Coronal Diagnostic Spectrometer
(CDS) onboard the Solar and Heliospheric Observatory (SOHO). There is
significant correlation between the He i and O v modulations, with O v
intensity leading He i intensity by 27.3 s ± 4.6 s but no significant
time shift in the Doppler shift. Cross-correlation between the O v
and Mg ix intensities reveals multiple maxima without correlation
between their Doppler shifts. Wavelet power analysis gives evidence
of intermittent chromospheric and transition-region oscillations with
periodicities in the 250-450 s range and of coronal oscillations in
the 110-300 s range. Wavelet phase difference analysis shows that
the determined time shift between variations of the He i and O v
intensities is dominated by waves with about 300 s periodicity. We
interpret these results as giving evidence of compressive waves that
propagate downward from the transition region to the chromosphere in
the particular chromospheric network. We discuss different scenarios
regarding origin and source localization of waves, and we speculate
on their role in coronal heating above chromospheric network.
Title: Hemispheric sunspot numbers {Rn} and {Rs}
from 1945-2004: catalogue and N-S asymmetry analysis for solar
cycles 18-23
Authors: Temmer, M.; Rybák, J.; Bendík, P.; Veronig, A.; Vogler,
F.; Otruba, W.; Pötzi, W.; Hanslmeier, A.
Bibcode: 2006A&A...447..735T
Altcode:
From sunspot drawings provided by the Kanzelhöhe Solar Observatory,
Austria, and the Skalnaté Pleso Observatory, Slovak Republic, we
extracted a data catalogue of hemispheric Sunspot Numbers covering
the time span 1945-2004. The validated catalogue includes daily,
monthly-mean, and smoothed-monthly relative sunspot numbers
for the northern and southern hemispheres separately and is
available for scientific use. These data we then investigated with
respect to north-south asymmetries for almost 6 entire solar cycles
(Nos. 18-23). For all the cycles studied, we found that the asymmetry
based on the absolute asymmetry index is enhanced near the cycle
maximum, which contradicts to previous results that are based on the
normalized asymmetry index. Moreover, the weak magnetic interdependence
between the two solar hemispheres is confirmed by their self-contained
evolution during a cycle. For the time span 1945-2004, we found that
the cycle maxima and also the declining and increasing phases are
clearly shifted, whereas the minima seem to be in phase for both
hemispheres. The asymmetric behavior reveals no obvious connection
to either the sunspot cycle period of ~11- or the magnetic cycle of
~22-years. The most striking excess of activity is observed for the
northern hemisphere in cycles 19 and 20.
Title: Hemispheric Sunspot Numbers 1945--2004: data merging from
two observatories
Authors: Temmer, M.; Rybák, J.; Bendík, P.; Veronig, A.; Vogler,
F.; Pötzi, W.; Otruba, W.; Hanslmeier, A.
Bibcode: 2006CEAB...30...65T
Altcode:
For the time span 1945--2004 from daily sunspot drawings northern
and southern relative sunspot numbers are extracted using drawings
provided by Kanzelhöhe Solar Observatory, Austria, and Skalnaté Pleso
Observatory, Slovak Republic. The derived data will be used to improve
and extend an already existing catalogue of hemispheric sunspot numbers
(Temmer et al., 2002). Since northern and southern solar hemispheres
do not evolve in phase during the cycle, hemispheric data are very
important for activity studies. In the present paper the compilation
of the data for the period 1945--2004 is described. Furthermore as a
quality check of the derived hemispheric data a regression analysis and
the comparison to the international hemispheric sunspot numbers from
the Sunspot Index Data Center for the time span 1992--2004 is presented.
Title: Periodical patterns in major flare occurrence and their
relation to magnetically complex active regions
Authors: Temmer, M.; Veronig, A.; Rybák, J.; Brajša, R.; Hanslmeier,
A.
Bibcode: 2006AdSpR..38..886T
Altcode:
A periodical occurrence rate of major solar flares (observed in hard
X-rays) of ∼24 days (synodic) was first reported by Bai (1987)
[Bai, T. Distribution of flares on the sun superactive regions and
active zones of 1980 1985. ApJ 314, 795 807, 1987] for the years 1980
1985. Here, we report a significant relation between the appearance of
the 24-day period in major Hα flares and magnetically complex sunspot
groups (i.e., including a γ and/or δ configuration). From synoptic
maps of magnetograms (NSO/KP) patterns in the magnetic flux evolution
are traced which might be the cause of the 24-day period observed in
flare activity.
Title: Acoustic Flux and Turbulence in the Solar Photosphere
Authors: Hanslmeier, A.; Kučera, A.; Rybák, J.; Wöhl, H.
Bibcode: 2006CEAB...30...11H
Altcode:
Using slit scans of solar photospheric spectral lines originating in
the middle photosphere a 2-D field on the Sun was obtained and the
occurrence of acoustic flux is investigated. As proxies for acoustic
flux generation enhanced turbulence (measured by fwhm variations) as
well as large continuum intensity values are used. The results show
that acoustic flux is not limited to the intergranular space and is
also produced by horizontal motions that may become supersonic leading
to turbulence. These motions lead to brightenings as it was predicted
by theoretical models.
Title: Intermediate-Term Periodicities in Some Solar Activity Indices
during Cycle 23
Authors: Ataç, T.; Özgüç, A.; Rybak, J.
Bibcode: 2005ESASP.600E.151A
Altcode: 2005dysu.confE.151A; 2005ESPM...11..151A
No abstract at ADS
Title: Hemispheric Sunspot Numbers RN and RS from 1945-2004: Extended
and Improved Catalogue
Authors: Temmer, M.; Rybák, J.; Veronig, A.; Bendík, P.; Vogler,
F.; Pötzi, W.; Otruba, W.; Hanslmeier, A.
Bibcode: 2005ESASP.600E..52T
Altcode: 2005ESPM...11...52T; 2005dysu.confE..52T
No abstract at ADS
Title: Influence of the 5-min oscillations on solar photospheric
layers. I. Quiet region
Authors: Odert, P.; Hanslmeier, A.; Rybák, J.; Kučera, A.; Wöhl, H.
Bibcode: 2005A&A...444..257O
Altcode:
Time series of 1D spectrograms are used to study the influence of the
5-min oscillations on intensity and velocity fields of different layers
of the quiet solar photosphere. We study the continuum intensity field
along with intensity and corresponding velocity patterns of the mid and
upper photosphere, obtained from two Fe lines. Oscillations seem to
dominate the intensity and velocity fields of the higher atmospheric
layers. Our results confirm the fast decay of the granular intensity
structure with height. From correlations of temperature structures
at three different photospheric levels we conclude that there are
rapid changes of the structures in the lower photosphere, which are
valid for the duration of the time series, while for the upper levels
changes of the stuctures are fainter and show significant periodic
character. The velocity pattern, on the other hand, shows a periodic
propagation through the photosphere. The tests of the influence of
seeing conditions on the data are considered.
Title: Statistical Analysis of Pulsations and Pulsations with Fibers
in the Range 800-2000 MHZ
Authors: Mészárosová, H.; Rybák, J.; Zlobec, P.; Magdalenić,
J.; Karlický, M.; Jiřička, K.
Bibcode: 2005ESASP.600E.133M
Altcode: 2005dysu.confE.133M; 2005ESPM...11..133M
No abstract at ADS
Title: Analysis of Dynamics of Loops in AN Active Region Associated
with a Small C-Class Flare
Authors: Gömöry, P.; Rybák, J.; Kucera, A.; Wöhl, H.
Bibcode: 2005ESASP.596E..56G
Altcode: 2005ccmf.confE..56G
No abstract at ADS
Title: VizieR Online Data Catalog: Hemispheric Sunspot Numbers
1945-2004 (Temmer+, 2006)
Authors: Temmer, M.; Rybak, J.; Bendik, P.; Veronig, A.; Vogler, F.;
Otruba, W.; Poetzi, W.; Hanslmeier, A.
Bibcode: 2005yCat..34470735T
Altcode:
From sunspot drawings provided by the Kanzelhoehe Solar Observatory,
Austria, and the Skalnate Pleso Observatory, Slovak Republic,
a data catalogue of hemispheric Sunspot Numbers covering the time
span 1945-2004 is extracted. The validated catalogue includes daily,
monthly-mean and smoothed-monthly relative sunspot numbers for the
northern and southern hemispheres separately and is available for
scientific use. Based on this data set an analysis concerning the
North-South asymmetry is made within this paper. (2 data files).
Title: Quasibiennial Oscillations of the North-South Asymmetry
Authors: Badalyan, O. G.; Obridko, V. N.; Rybák, J.; Sýkora, J.
Bibcode: 2005ARep...49..659B
Altcode:
The north-south (N-S) asymmetry of the solar activity (A), which
reflects differences in the behavior of the northern and southern
hemispheres of the Sun, is studied using data on the brightness of the
coronal green line, the total number and area of sunspots, and the net
magnetic flux. The spatial and temporal distributions and correlations
between the A values represented by these indices are considered. The
characteristic time variations in A are similar for all the indices,
on both long and short time scales. Quasibiennial oscillations (QBOs)
can be traced in the asymmetries of all four indices. A detailed study
of the QBOs is carried out based on spectral-variation and wavelet
analyses. Long-term increases and decreases occur synchronously in
the asymmetries of various indices and are much more pronounced in A
than in the indices themselves. A negative correlation between the
power of the QBOs and the asymmetry of A can be traced; it is most
clearly manifest as a substantial diminishing of the QBOs during
the mid-1960s, which coincided with an especially strong increase in
A. Our analysis shows that the N-S asymmetry is probably a fundamental
property that controls the coupling and degree of coincidence between
the magnetic-field-generation mechanisms operating in the northern
and southern hemispheres.
Title: What causes the 24-day period observed in solar flares?
Authors: Temmer, M.; Rybák, J.; Veronig, A.; Hanslmeier, A.
Bibcode: 2005A&A...433..707T
Altcode:
Previous studies report a 24-day (synodic) period in the occurrence
rate of solar flares for each of the solar cycles studied, Nos. 19-22
(Bai 1987, ApJ, 314, 795; Temmer et al. 2004, Sol. Phys. 221,
325). Here we study the 24-day period in the solar flare occurrence
for solar cycles 21 and 22 by means of wavelet power spectra together
with the solar flare locations in synoptic magnetic maps. We find
that the 24-day peak revealed in the power spectra is just the
result of a particular statistical clumping of data points, most
probably caused by a characteristic longitudinal separation of about
+40circ to +50circ of activity complexes in
successive Carrington rotations. These complexes appear as parallel,
diverging or converging branches in the synoptic magnetic maps and
are particularly flare-productive.
Title: Analysis of Doppler Shifts of Spectral Lines Obtained by the
CDS/SOHO Instrument
Authors: Gömöry, P.; Rybák, J.; Kučera, A.; Curdt, W.; Wöhl, H.
Bibcode: 2005ASSL..320..203G
Altcode: 2005smp..conf..203G
No abstract at ADS
Title: On the Behaviour of a Blinker in Chromospheric and Transition
Region Layers
Authors: Tomasz, F.; Rybák, J.; Kučera, A.; Curdt, W.; Wöhl, H.
Bibcode: 2005ASSL..320..207T
Altcode: 2005smp..conf..207T
No abstract at ADS
Title: Variability and Dynamics of the Outer Atmospheric Layers in
the Quiet Solar Network
Authors: Gömöry, P.; Rybák, J.; Kučera, A.; Curdt, W.; Wöhl, H.
Bibcode: 2005HvaOB..29...71G
Altcode:
A detailed study of the temporal evolution of the chromospheric He
I 584.33 Å and the transition region O V 629.73 Å emission line
intensities of quiet supergranular network of the Sun near disk centre
observed with Coronal Diagnostic Spectrometer (CDS) is presented. A
wavelet analysis of the 1729 s (28.8 min) long temporal series was
performed in order to derive the duration as well as periods of the
chromospheric and the transition region oscillations. The He I line
intensities show significant power for periods around 300 s (3.3 mHz),
which is relevant only in the second half of the observing sequence
(between 800 -- 1700 s). The temporal evolution corresponding to the
O V line intensities shows strong power around the period of 400 s
(2.5 mHz), which is significant during the whole observing sequence
as well as the oscillation of lower power for periods of around 250 s
(4.0 mHz), which is present only in the middle of the observing sequence
(between 700 -- 1300 s).
Title: Overview of the flare index during the maximum phase of the
solar cycle 23
Authors: Ataç, T.; Özgüç, A.; Rybák, J.
Bibcode: 2005AdSpR..35..400A
Altcode:
A brief description and final results of the flare index of solar
activity for the maximum phase of the cycle 23 are given. The patterns
of similar activity indices that arise under different physical
conditions during the cycle 23 were compared with the flare index. The
intermediate-term periodicities in the daily flare index data for the
full disc and for the northern and the southern hemispheres of the Sun
were calculated before by the authors using the Fourier transform, and
it was found that 64, 125 days periodicities are in operation during
the maximum phase of the solar cycle 23. In this paper, we examined
these periodicities in time domain by using the wavelet transform. The
results of this transform show that during the maximum phase of the
current solar cycle a very prominent multi-peaked structures exist in
each solar hemisphere and the occurrence of flare index power is highly
intermittent in time. Moreover, it is found that the flare activity
of the opposite hemispheres were not well time-synchronized during
the maximum phase. The flare activity of the southern hemisphere was
observed to be more dominant in determining the characteristics of
the flare activity in the solar cycle 23.
Title: Intermittence of the short-term periodicities of the flare
index
Authors: Rybák, J.; Özgüç, A.; Ataç, T.; Sözen, E.
Bibcode: 2005AdSpR..35..406R
Altcode:
Intermittence of the short-term periodicities (25-35 days) of the
flare index are investigated using the wavelet transform method for
the full-disc and for the northern and the southern hemispheres of
the Sun separately over the epoch since 1966 until 2002. The wavelet
transform results show that occurence of periodicities of flare index
power is highly intermittent in time. The period-averaged wavelet
power of the flare index presents this fact very clearly displaying
independence of flaring activity on the solar hemispheres in several
time intervals over almost four solar cycles under study. Moreover
correlations of the period-averaged wavelet power of the flare index
for the separate hemispheres and for the full-disc reveal significantly
stronger relation between the full-disc and the northern hemisphere than
between the full-disc and the southern hemisphere while no significant
correlations was found between the hemispheres one another.
Title: High Resolution Observations of a M5.4 Flare
Authors: Kučera, A.; Wöhl, H.; Rybák, J.; Gömöry, P.; Tomasz, F.
Bibcode: 2005HvaOB..29..177K
Altcode:
Hα observations of a M5.4 flare taken in the active region NOAA 10646
with the Vacuum Tower Telescope at Observatório del Teide, Tenerife,
on July 13, 2004 are presented. The temporal evolution of the area
of the flare and its morphological changes are investigated and
discussed. Simultaneous observations of the flare in EUV lines taken
with CDS/SOHO instrument are shown and additional data from GOES-10
instrument are compared.
Title: Coronal manifestations of solar variability
Authors: Sýkora, J.; Rybák, J.
Bibcode: 2005AdSpR..35..393S
Altcode:
This contribution is mostly about phenomenology of what we see
in space-time evolution of coronal green line brightness (CGLB),
including its cyclic variations. Our own database (1943-2001) of the
coronal Fe XIV 530.3 nm emission line intensities is used to display
different aspects of the large-scale CGLB regularities and cyclic
behaviour. Hemispheric asymmetry and relation of the longitudinal CGLB
distribution to the rotational characteristics of the solar corona
are particularly underlined.
Title: Influence of Transition Region Blinker on the Surrounding
Chromospheric and Coronal Plasma
Authors: Tomasz, F.; Rybák, J.; Kučera, A.; Curdt, W.; Wöhl, H.
Bibcode: 2005HvaOB..29..197T
Altcode:
Results of spectral analysis of a blinker observed in the transition
region O VI 1037.63 Å line and in the chromospheric Ly β 1025.72
Å line which were acquired using the SUMER spectrometer are
presented. Chromospheric and coronal plasma in the vicinity of the
blinker are investigated using also TRACE Ly α, UV continuum and Fe IX
channels. It was found that initial release of energy was localized in
the transition region and plasma has been spreading from transition
region as a bi-directional jet. Energy reached chromosphere ∼60
seconds after primary emission in the o6 line. There were detected
enhanced emissions for about 25-38% in the chromospheric Lyα and UV
continuum. Spatial extent of the blinker response is 6'' along the slit
in the Lyα filtergram what is ∼3'' less than extent of the blinker
in the o6 line. Maximum extent of the blinker response is 7.5'' in
Lyα filtergram. Although, both Lyα and UV continuum reflect physical
conditions in chromosphere, their patterns are completely different:
pattern of the blinker response is compact in the Lyα and UV continuum
shows non-compact structure below the transition region blinker. Coronal
plasma was not influenced by the blinker although plasma moving toward
observer was detected in the final phase of evolution of the blinker.
Title: Observational Evidences for Heating of the Solar Corona
by Nanoflares in the Network Derived from the Transition Region
Spectral Lines
Authors: Rybák, J.; Kucera, A.; Curdt, W.; Wöhl, H.
Bibcode: 2004ESASP.575..529R
Altcode: 2004soho...15..529R
No abstract at ADS
Title: Dynamics of the Quiet Upper Solar Atmosphere in the Network
Authors: Gömöry, P.; Rybák, J.; Kucera, A.; Curdt, W.; Wöhl, H.
Bibcode: 2004ESASP.575..400G
Altcode: 2004soho...15..400G
No abstract at ADS
Title: Evaluation of the short-term periodicities in the flare index
between the years 1966 2002
Authors: Özgüç, Atila; Ataç, Tamer; Rybák, Ján
Bibcode: 2004SoPh..223..287O
Altcode:
The short-term periodicities of the flare index are investigated in
detail using Fourier and wavelet transforms for the full disc and for
the northern and the southern hemispheres of the Sun separately over the
epoch of almost 4 cycles (1966-2002). The most pronounced power peaks
were found by the Fourier transform to be present at 25.6, 27.0, 30.2,
and 33.8 days. The wavelet transform results show that the occurrence
of periodicities of flare index power is highly intermittent in time. A
comparison of the results of the Fourier transform and the time-period
wavelet transform of the flare index time series has clarified the
importance of different periodicities, whether they are or are not
the harmonics of the basic ones, as well as the temporal location of
their occurrence. We found that the modulation of the flare index due
to the 27-day solar rotation is more pronounced during the declining
portion of solar cycle than during the rising portion.
Title: Two-dimensional spectroscopic time series of solar granulation
Authors: Hanslmeier, A.; Kucera, A.; Rybák, J.; Wöhl, H.
Bibcode: 2004SoPh..223...13H
Altcode:
In this paper we investigate the dynamics of the solar granulation
by analyzing time series of 2D spatially highly resolved
spectrograms. These were obtained by spatial scans covering a field
of 12 8″ × 20″. The advantage of this method is a high spectral
resolution, however, the data are not taken simultaneously and to
cover the field described above 50 exposures taken sequentially in
time are necessary. Therefore, to obtain one map about 2 minutes are
required. Plots of the evolution of different line parameters are
given as well as the decay of correlation functions. The correlations
between the first map of line parameters and successive maps (which are
separated by about 2 minutes) were investigated showing a rapid decay
down to a correlation coefficient of 0.4 within 4 minutes, the velocity
pattern in the field observed varies on smaller time scales. The
temporal variation of correlation between the line parameters for the
different lines shows a periodic signal related to 5-min oscillations
which could not be totally filtered. The evolution of the correlation
functions between line parameters is analyzed which gives an error
estimate of all correlation values found in the literature. For
the first time it is explicitly shown how evolution in a selected
photospheric field influences the evolution of granular/intergranular
structures.
Title: Indications of shock waves in the solar photosphere
Authors: Rybák, J.; Wöhl, H.; Kučera, A.; Hanslmeier, A.;
Steiner, O.
Bibcode: 2004A&A...420.1141R
Altcode:
High resolution observations of solar granulation near the solar limb
are used in a search for hydrodynamic shocks caused by an abrupt
braking of the fast (probably supersonic) horizontal flow of the
granular plasma towards the intergranular lane. Shock signatures in
the spectral line of Fe II 6456.38 Åof one particular observed shock
event are investigated in detail. Evolution, amplitude, and spatial
relation of the spectral line characteristics of the shock event are in
agreement with predictions from numerical simulations for such shock
phenomena in the solar photosphere. The dimensions and amplitudes of
the observed shock signatures are comparable to predicted values when
seeing and instrumental effects as well as a possible obliqueness of
the shock front with respect to the observer's line-of-sight are taken
into account. The temporal evolution of such an event is observed for
the first time. The stable and declining phase of the event were studied
for a time period of almost 2 min. A particular relationship was found
between the shock event and a nearby G-band bright point located 2''
from the shock event. It is suggestive that the observed shock is a
causal consequence of the magnetic flux concentration, traced by the
G-band bright point. Such a type of shock can appear outside the flux
concentrations as a consequence of a rapid flux-tube motion.
Title: On the 24-day period observed in solar flare occurrence
Authors: Temmer, M.; Veronig, A.; Rybák, J.; Brajša, R.; Hanslmeier,
A.
Bibcode: 2004SoPh..221..325T
Altcode:
Time series of daily numbers of solar Hα flares from 1955 to
1997 are studied by means of wavelet power spectra with regard to
predominant periods in the range of ∼ 24 days (synodic). A 24-day
period was first reported by Bai (1987) for the occurrence rate of
hard X-ray flares during 1980-1985. Considering the northern and
southern hemisphere separately, we find that the 24-day period is not
an isolated phenomenon but occurs in each of the four solar cycles
investigated (No. 19-22). The 24-day period can be established also
in the occurrence rate of subflares but occurs more prominently in
major flares (importance classes ≥ 1). A comparative analysis of
magnetically classified active regions subdivided into magnetically
complex (i.e., including a γ and/or δ configuration) and non-complex
(α, β) reveals a significant relation between the appearance of
the 24-day period in Hα flares and magnetically complex sunspot
groups, whereas it cannot be established for non-complex groups. It is
suggested that the 24-day period in solar flare occurrence is related
to a periodic emergence of new magnetic flux rather than to the surface
rotation of sunspots.
Title: On Relations among the Calibrated Parameters of the Transition
Region Spectral Line
Authors: Rybák, J.; Kucera, A.; Curdt, W.; Wöhl, H.
Bibcode: 2004ESASP.547..311R
Altcode: 2004soho...13..311R
SUMER/SOHO measurements of the O VI 1031.93 Å emission line (280000
K) in the network and internetwork of the transition region of the
quiet solar atmosphere are used for a statistical analysis of the
calibrated spectral parameters: the central line intensity (energetic
units), the line width (m Å) and the Doppler shift (km/s). A detailed
procedure is performed in order to determine the absolute wavelength
calibration of the spectra and Doppler shifts using simultaneously
observed chromospheric O I 1027.44 Å and 1028.15 Å emission lines
(10 000K). The spectral parameters of the O VI line are derived for
both single and double Gaussian fitting of the line according to the
latest findings on the multi-component nature of the transition region
line profiles. Reliability of the absolute wavelength calibration and
effects of two classes of the transition region transient events -
explosive events and blinkers - are discussed in relation to the
overall dependencies of the spectral parameters.
Title: Evidence of the fundamental periodicity in the flare index
between the years 1966-2002
Authors: Özgüç, A.; Ataç, T.; Rybák, J.
Bibcode: 2004IAUS..223..557O
Altcode: 2005IAUS..223..557O
No abstract at ADS
Title: Merging two data sets of hemispheric Sunspot Numbers
Authors: Rybák, J.; Bendík, P.; Temmer, M.; Veronig, A.; Hanslmeier,
A.
Bibcode: 2004HvaOB..28...63R
Altcode:
First results on merging two data sets of hemispheric sunspot numbers
-- from the Kanzelhöhe Solar Observatory and the Skalnaté Pleso
Observatory -- for the time span 1977 -- 1978 are presented. A total
coverage of 86% was reached for the merged data set. In order to have
a homogeneous time series, the daily sunspot numbers for the full disk
from both observing stations were normalized to the international
relative sunspot number of the day. The derived hemispheric sunspot
numbers from Kanzelhöhe and Skalnaté Pleso Observatory %compared
for 290 common observing show very high correlations (r ≳ 0.95), and
the estimated data noise yields significant differences only for small
values of sunspot numbers. These outcomes demonstrate the high potential
of the applied merging procedure, and are the basis for an ongoing
project to derive hemispheric sunspot numbers back to the year 1945
using sunspot drawings from Kanzelhöhe and Skalnaté Pleso Observatory.
Title: On Mutual Relation Among the Outer Atmospheric Layers in
Network: SOHO/CDS Study
Authors: Gömöry, P.; Rybák, J.; Kucera, A.; Curdt, W.; Wöhl, H.
Bibcode: 2004ESASP.547..303G
Altcode: 2004soho...13..303G
SOHO/CDS measurements of emission in the network of the quiet solar
atmosphere near disk center were used to derive mutual relations
of emission and dynamics in different temperature regimes in/above
supergranular network. Cross-correlation functions of the line
intensities and the Doppler shifts of the chromospheric line He I 584.3
Å, the transition region line O V 629.7 Å and the coronal line Mg
IX 396.1 Å were calculated in order to study relative variability
of different atmospheric layers. Relatively high correlations were
found between the intensities and the Doppler shifts of the He I and
O V lines with two peaks of the intensity correlation function. The
maximum value of the correlation of intensities (CC = 0.86) was reached
for the zero time lag and the second maximum (CC = 0.78) was obtained
for the time lag -190s (O V precedes He I). Only one sharp peak (CC =
0.55) was detected in the Doppler shift correlation function of these
lines for the zero time lag. For the correlation of O V and Mg IX
intensities one peak (CC = 0.57) of the correlation function was also
discovered for the time lag +150s (Mg IX falls behind O V). In contrast,
no correlation was obtained for the Doppler shifts of the O V and Mg
IX lines. Summarizing we can assume clear relation in energy transfer
and/or mass motion between chromosphere and transition region but no
relation was found between corona and the lower parts of the solar
atmosphere above the particular network under study.
Title: Importance of magnetically complex active regions on solar
flare occurrence
Authors: Temmer, M.; Veronig, A.; Rybák, J.; Brajša, R.; Hanslmeier,
A.
Bibcode: 2004HvaOB..28...95T
Altcode:
Daily numbers of solar Hα flares from 1955 to 1997 and daily numbers
of magnetically classified active regions for the time span 1964--1997
are studied applying wavelet power spectra. The occurrence of dominant
periods in the range of ∼24 days (synodic) is investigated considering
the northern and southern hemisphere separately. From the flare events
it is revealed that the 24-day period occurs in each of the four solar
cycles investigated (no. 19--22). The 24-day period can be established
also in the occurrence rate of subflares but occurs more prominently
in major flares (importance classes ≥1). Magnetically complex active
regions, i.e. including a γ and/or δ configuration, show the 24-day
period closely related to those found for major Hα flares, whereas
it cannot be established for non-complex α, β groups.
Title: Velocity field in the intergranular atmosphere
Authors: Kučera, A.; Koza, J.; Bellot Rubio, L. R.; Hanslmeier, A.;
Rybák, J.; Wöhl, H.
Bibcode: 2004HvaOB..28...19K
Altcode:
The line-of-sight velocity ľand macroturbulent velocity are studied
in the centre of the intergranular space in the solar photosphere. An
inversion method is applied to a 4-min time sequence of Stokes
I spectra of the 5, 6 and 7 lines observed with high spatial and
temporal resolutions at solar disk centre. The results are presented
in the form of the functional dependence of ľ(logτ5,t)
and (t) on the continuum optical depth τ5 at 500 nm and
time t. A ľof several hundreds of meters per second was found in the
upper photosphere (logτ5≤-1.5), where the plasma flows
away from the observer. On the contrary, upflows directed toward the
observer were found in deeper layers (logτ5>-1.5). The
typical value of in the centre of the intergranular space is found to be
∼1.7 kms, which is about 0.5 kms greater than in the adjacent granule.
Title: SUMER/SOHO and TRACE Study of the Transition Region Blinker
Authors: Tomasz, F.; Rybák, J.; Kucera, A.; Curdt, W.; Wöhl, H.
Bibcode: 2004ESASP.547..307T
Altcode: 2004soho...13..307T
The most prominent transient event is presented from an extensive
search for the transition region internetwork activity in the quiet
solar atmosphere performed by SUMER/SOHO spectrometer and TRACE. SUMER
spectra of Ly line (1025.4 Å), two C II lines (1036.3 Å, 1037.0 Å)
and O VI line (1037.61 Å) were used for determination of the spatial
and temporal evolution of the transient event in the transition
region. TRACE images taken in the 1216 Å passband, UV continuum
(1700 Å) and Fe IX line (171 Å) were utilized in order to gain
information about large-scale coronal structures and small-scale
chromospheric variability in the vicinity of the transient event. The
main physical and geometrical parameters of the event were derived
for the transition region O VI line: the spatial extent of 11 000 km,
duration for 9 minutes, intensity enhancement factor of 7 and the
Doppler velocities of both signs up to 15 km/s. According to these
values the event was identified as a transition region blinker. High
deviations of the acquired O VI line profiles from single-Gaussian and
some multi-Gaussian profiles reveal dynamics of the event - occurrence
of the bidirectional jet which is not typical for blinkers. Besides
rapid changes in intensity and in velocity, a rapid increase by a
factor of 4.2 was found in the Gaussian width of O VI line as compared
to the internetwork. Surrounding chromospheric and coronal structures
around the event are discussed on base of the simultaneously taken
TRACE images.
Title: One-dimensional spectroscopy of the solar photosphere
Authors: Odert, P.; Hanslmeier, A.; Rybák, J.; Kučera, A.; Wöhl, H.
Bibcode: 2004HvaOB..28...37O
Altcode:
Data from a time series of spectrograms were used to study
correlative relationships between intensity and velocity in the solar
photosphere. The variations along the slit of the line parameters from
two Fe lines lying in the visible range of the spectrum were used. The
formation height difference of these lines is over 300 km. The temporal
variations of the correlation coefficients were studied, they showed
a strong influence of the 5 min-oscillations.
Title: Proper motions of sunspots - new data and further results
Authors: Wöhl, H.; Brajša, R.; Kučera, A.; Ruždjak, V.; Rybák, J.
Bibcode: 2004HvaOB..28...47W
Altcode:
The attempts to investigate patterns of motions of main spot components
and small pores in complex sunspot groups were continued. The data
discussed stem mainly from observations at Hvar/HR and Tatranská
Lomnica/SK. Two historic collections of photographic plates are
included: The plate archives of the former Fraunhofer Institute and
that of photographic plates taken at Skalnate Pleso/SK.
Title: Aspects of the solar variability in its coronal manifestations
Authors: Sykora, J.; Rybak, J.
Bibcode: 2004cosp...35.1243S
Altcode: 2004cosp.meet.1243S
Temporal and spatial organizations of the solar corona brightness
are well dependent from evolution, topology and strength of the
solar magnetic field. On the other hand, all the activities,
regularities, cyclicities and asymmetries observed in the solar
corona, undoubtedly, modulate physical processes in the heliosphere,
so contributing to creation of the space weather. Thus, all the
findings about variabilities in the solar corona may contribute to
a better understanding of both the lined topics. The large-scale and
long-term distributions of the coronal Fe XIV 530.3 nm emission line
brightness are obtained from analysis of the database covering the
1943-2001 period. We demonstrate and discuss a fine structuralization
of the butterfly diagram, existence of "active longitudes", presence of
the double maxima in the solar cycles, N/S asymmetry and a particular
relevance of the solar N and S middle-latitude zones for displaying
the coronal variability and its responses in the heliosphere.
Title: Periodical patterns in major flare occurrence and their
relation to magnetically complex active regions
Authors: Temmer, M.; Veronig, A.; Rybak, J.; Brajsa, R.; Hanslmeier, A.
Bibcode: 2004cosp...35.1395T
Altcode: 2004cosp.meet.1395T
A periodical occurrence rate of solar major flares (observed in
hard X-rays) of about 24 days (synodic) was first reported by Bai
(1987) for the years 1980--1985. Its origin is still far from being
understood. Applying wavelet analyses for daily numbers of Hα flare
events covering almost four entire solar cycles (no. 19--22) reveals a
24-day period in each of the cycles studied. This can be established
primarily in the occurrence rate of major flares but is also seen
in subflares. Since large flares occur preferentially in association
with active regions of complex magnetic configuration a comparative
study of magnetically classified active regions, subdivided into
magnetically complex (i.e. including a γ and/or δ configuration)
and non-complex (α, β) was performed. A significant relation
between the appearance of the 24-day period in major Hα flares and
magnetically complex sunspot groups is found, whereas it cannot be
established for non-complex groups. From solar rotation studies based
on tracing sunspots practically no siderial rotation velocities as high
as 16 deg/day (which corresponds to a synodic period of ∼24 days)
are reported. Thus the cause of the 24-day period is very likely not
related to solar surface rotation. Alternatively it might be due to
periodical patterns in magnetic flux emergence which is an important
driver of flare eruptions. We test this hypothesis by investigating
synoptic maps of magnetograms (National Solar Observatory/Kitt Peak)
for selected time ranges in which the 24-day period is revealed for
both flares and magnetically complex active regions.
Title: Evaluation of the short-term periodicities in the flare index
between the years 1966-2001
Authors: Ozguc, A.; Atac, T.; Rybak, J.
Bibcode: 2004cosp...35..152O
Altcode: 2004cosp.meet..152O
The short-term periodicities of the flare index are investigated in
detail using Fourier and wavelet transforms for the total surface and
for the northern and the southern hemispheres of the Sun separately
over the epoch of almost 4 cycles (1966-2001). The most pronounced
power peaks were found by the Fourier transform to be present at 25.3,
27.0, 29.1, and 33.8 days. The wavelet transform results show that
the occurrence of flare index power is highly intermittent in time. A
comparison of the results of the Fourier transform and the time-period
wavelet transform of the flare index time series has clarified the
importance of different periodicities, whether they are or are not
the harmonics of the basic ones, as well as the temporal location of
their occurrence. Because we found that the modulation of the flare
index due to the 27-day solar rotation is more pronounced during the
declining portion of solar cycle than during the rising portion.
Title: Green corona versus photospheric magnetic flux: solar cycle
dependence
Authors: Dorotovič, I.; Rybák, J.
Bibcode: 2003ESASP.535...87D
Altcode: 2003iscs.symp...87D
The relation between the green corona and the photospheric magnetic flux
has been analyzed over the period from 1995 to 2001. The homogeneous
dataset of the green coronal line intensities and the Kitt Peak
magnetic flux data were used for determining this relation. Focus
was on the solar cycle dependence of the numerical relation between
these two parameters has been investigated. Any overall fit with fixed
parameters for the period of several years was shown to be unrealistic
for describing this relation because the fit was found to be time
dependent. The coefficients of the linear fit used in the paper show
quite significant changes in their values with time. Moreover, the
inverse relation of the absolute and the linear co-efficients of the
fit was obtained during the ascending phase of the solar cycle between
1998 and 2001. Therefore, in order to extrapolate magnetic flux data
before 1975 using the existing longer datasets of the green coronal
intensities, it is necessary to take into account the revealed solar
cycle dependence of their relation and to estimate the quantitative
parameters of the relation separately for the individual phases of
the solar cycle.
Title: N-S asymmetry of solar activity and quasi-biennial oscillations
Authors: Badalyan, O. G.; Obridko, V. N.; Rybák, J.; Sýkora, J.
Bibcode: 2003ESASP.535...63B
Altcode: 2003iscs.symp...63B
Space-time distribution and mutual correlation of the N-S
asymmetry in various indices of solar activity are considered. It
is shown that changes in the N-S asymmetry variation both at short
and long time scales are consonant in all activity indices under
consideration. Quasi-biennial variations of the asymmetry index and
their space-time distribution are revealed and examined. The conclusion
can be drawn that the N-S asymmetry is a specific independent and very
promising tool for analysis of the solar activity variations.
Title: On rotational patterns of the solar magnetic field
Authors: Temmer, M.; Veronig, A.; Rybák, J.; Hanslmeier, A.
Bibcode: 2003ESASP.535..157T
Altcode: 2003iscs.symp..157T
Solar magnetic field variations (NSO/Kitt Peak data) through solar cycle
23 with respect to rotational modulations are analyzed. A comparative
study to solar cycles 21 and 22 is performed. The results are compared
to the rotational behavior of activity tracers like sunspots and solar
Hα flares. Periodical occurrences of flares often match the 27-day
solar rotation due to recurrent stable sunspot groups and complexes
of activity which likely produce more flare events than short-living
small sunspots. However, periods with strong deviations from the 27-day
period are obtained for higher energetic flares. The solar magnetic
field is found to vary on similar time scales, which suggests a close
relation to the occurrence of strong flare events.
Title: Short-term periodicities in the flare index between the
years 1966-2001
Authors: Özgüç, A.; Ataç, T.; Rybák, J.
Bibcode: 2003ESASP.535..141O
Altcode: 2003iscs.symp..141O
A brief description and the results of the temporal variability
of the flare index over the epoch of almost 4 cycles (1966-2001)
are presented. Using Fourier and wavelet transforms the short-term
periodicities in the daily flare index data for the total surface of
the Sun are presented. A significant variability was found for all
periods. The wavelet transform results show that the occurrence of
flare index power is highly intermittent in time.
Title: On evolution of the photospheric magnetic fields on the
Sun: separation of active/dissipative/background fields by optimum
thresholds
Authors: Mocák, M.; Rybák, J.
Bibcode: 2003ESASP.535..137M
Altcode: 2003iscs.symp..137M
The distribution of the magnetic flux in the Sun's photosphere is
studied using NSO/Kitt Peak Carrington rotaton maps of the magnetic
flux in the period from 1975 to 2003. In principle it is possible
to separate the magnetic fields using these magnetic data into three
types: background fields, dissipative fields coming from the active
regions and the active region fields themselves. This contribution
discusses determination of the optimum thresholds for such separations
of the magnetic fields. The threshold between background fields and
dissipative fields is derived from the average minimal values of the
magnetic flux measured in high latitudes where/when no active region
flux and only minumum of the dissipative flux are detected. It's
value is 2.8 Gauss. Contrary it is presented that there is no common
value of the threshold between the dissipative fields and the active
regions fields valid for the whole period under study. It is shown that
value of this threshold is in fact unique not only for each Carrington
rotation map but that it is specific even for each particular active
region. Usually accepted value of 25 Gauss seems to be only the minimal
limit of this threshold. Its maximal limit is exceeding value of 110
Gauss. Nevertheless just separation between the background fields
and the sum of the dissipative and the active region fields allows to
discuss the temporal and latitudinal behaviour of these two types of
the magnetic fields during evolution of the solar cycles.
Title: Mutual relations of the intermediate periodicities of the
Wolf sunspot number
Authors: Rybák, J.; Karlovský, V.
Bibcode: 2003ESASP.535..145R
Altcode: 2003iscs.symp..145R
First results of an analysis of the temporal variability of the solar
activity represented by the relative Wolf sunspot number in the epoch
1850-2002 are presented within range of the intermediate periods from
0.3 up to 4 years. The daily data of the Wolf number has been utilized
using the wavelet transform while different ways of estimation of the
significance of periods were applied. The performed analysis was focused
on a search for possible mutual relations between the appearance
of the intermediate periods and their connection to the overall
course of the cycle of solar activity. Results have revealed several
significant periods but, in general, only of an intermittent character
of appearance. Besides some other periods especially that of ~2-year,
~1.3-year, ~0.75-year and 4-year were found to be significant in several
instances of time. Comparison of these results allow to conclude that
the quasi-biennial period is not related to any particular phase of
the solar cycle and that presence of the 4-year period is independent
from the quasi-biennial period. Additionally the well-known 155-day
period was confirmed with its particular intermittent appearance both
in phase and out of phase of the 1.3-year period in difference time
intervals. Possible influence of estimation of the background noise
for determination of the significance of periods is discussed as well.
Title: On the Shape of Cosmic Ray Modulation during Evenand
Odd-Numbered Solar Activity Cycles
Authors: Kudela, K.; Storini, Marisa; Massetti, Stefano; Rybak, Jan
Bibcode: 2003ICRC....7.4095S
Altcode: 2003ICRC....7.4095K; 2003ICRC...28.4095S
Data from several neutron monitors are used to investigate the
cosmic ray modulation for different rigidity intervals in the period
1953-2002. From the shape of the cosmic ray modulation it turns out
that the ∼1.3-yr periodicity, identified also by the use of the
wavelet technique, results highly significant during the second stage
of cosmic ray modulation in even/odd heliomagnetic semicycles.
Title: Temporal variability of the flare index (1966-2001)
Authors: Özgüç, Atila; Ataç, Tamer; Rybák, Ján
Bibcode: 2003SoPh..214..375O
Altcode:
A brief description and study of the temporal variability of the flare
index over the epoch of almost 4 cycles (1966-2001) are presented. Using
Fourier and wavelet transforms the long- and the intermediate-term
periodicities in the daily flare index data for the total surface and
for the northern and the southern hemispheres of the Sun are given in
detail. A significant variability was found for all periods including
those of 150 days and 1.3 years. The wavelet transform results show
that the occurrence of flare index power is highly intermittent in
time. A comparison of the results of the Fourier transform and the
time-period wavelet transform of the flare index time series has
clarified the importance of different periodicities, whether they are
or are not the harmonics of the basic ones, as well as the temporal
location of their occurrence.
Title: Dynamics and turbulence of the chromospheric layers of a
flaring atmosphere
Authors: Brčeková, K.; Kučera, A.; Hanslmeier, A.; Rybák, J.;
Wöhl, H.
Bibcode: 2003AN....324..366B
Altcode:
No abstract at ADS
Title: Transition region blinker - spatial and temporal behaviour
Authors: Tomasz, F.; Rybák, J.; Kučera, A.; Curdt, W.; Wöhl, H.
Bibcode: 2003HvaOB..27...75T
Altcode:
From an extensive search for transition region internetwork activity
in the quiet Sun atmosphere the most prominent transient event is
presented. The basic physical and geometrical parameters of this event
are derived from the O VI 1037.61 Å emission spectral line. The spatial
extent of 11 000 km, duration for 9 minutes, intensity enhancements
factor of 7 and large Doppler velocities of both signs were estimated
for the event. According to these values this event was identified as
a transition region blinker.
Title: Proper motions of sunspot groups
Authors: Wöhl, H.; Brajša, R.; Kučera, A.; Ruždjak, V.; Rybák, J.
Bibcode: 2003HvaOB..27....1W
Altcode:
Attempts to investigate typical patterns of motions of main spot
components and small pores in complex sunspot groups are described. The
data used up to now stem from observations at Hvar/HR, Tatranská
Lomnica/SK, Izaña/E, Debrecen/H and from the MDI instrument on
SoHO. Preliminary results are presented.
Title: Evolution of temperature in granule and intergranular space
Authors: Koza, J.; Bellot Rubio, L. R.; Kučera, A.; Hanslmeier, A.;
Rybák, J.; Wöhl, H.
Bibcode: 2003AN....324..349K
Altcode:
The temporal evolution of temperature in a dissolving granule and
in an adjacent intergranular space is presented. The semi-empirical
evolutionary models have been calculated using an inversion method
applied to 4-min time series of Stokes I spectral line profiles. The
models are presented in the form of the functional dependence of
temperature T(log tau_5 ,t) on optical depth tau_5 at 500 nm and time
t. The observed disappearance of the granule is accompanied with overall
cooling of the granular photosphere. Temperature changes greater than
100 K have been found in deeper (log tau_5 >=0) and upper layers
(log tau_5 <=-2) whereas the intermediate layers are thermally
stable. The intergranular space, which is 2 arcsec off the granule,
keeps the temperature structure of the layers from log tau_5 =0.5 to
log tau_5 =-2 without global evolutionary changes except short-term
and spatially confined heating. Finally, the significant temperature
changes in the upper layers (log tau_5 <=-2.5) observed during the
time interval of 4 min are found to be typical for the granular and
intergranular photosphere.
Title: Observational evidence for a shock event in the solar
granulation
Authors: Kučera, A.; Rybák, J.; Hanslmeier, A.; Wöhl, H.
Bibcode: 2003HvaOB..27...25K
Altcode:
High resolution spectra of Fe II 6456.39 Å line are used to investigate
a shock in the solar granulation. The changes of the main spectral
characteristics measured in the shock area are in a good agreement with
the characteristics predicted with theory. The analysis of the shock,
made in the past by several authors was extended in this work to the
analysis of a temporal development of the shock event. The 2 minutes
duration of a stable and declining phases of the event was studied. We
conclude that the observed shock belonged to the particular type of
shock generated as a consequence of the swaying motion of the magnetic
flux tube concentrated in the intergranular lane. Such type of shock
was proposed by numerical simulations made by Steiner et al. 1998.
Title: Rotational modulation of northern and southern activity tracers
Authors: Temmer, M.; Veronig, A.; Rybák, J.; Hanslmeier, A.
Bibcode: 2003HvaOB..27...59T
Altcode:
We study solar activity phenomena, Hα flares and sunspots, with respect
to their periodical occurrence related to the solar rotation. The
analysis is carried out separately for the northern and the southern
hemisphere. Furthermore, flare occurrences are studied with respect
to different importance classes, and the results are compared to
the predominant periods derived from Sunspot Numbers. Significant
asymmetries are obtained between the northern and southern activity for
both Sunspot Numbers and flare occurrences. Differences between Sunspot
Numbers and flares result particularly when only higher energetic
flares are considered. A 24-day period is found for large flare events
in both hemispheres which is not detected in Sunspot Numbers.
Title: Transition region eruptive event observed with SOHO/CDS in
the quiet Sun network
Authors: Gömöry, P.; Rybák, J.; Kučera, A.; Curdt, W.; Wöhl, H.
Bibcode: 2003HvaOB..27...67G
Altcode:
CDS observations of the quiet Sun network in the chromospheric He I
584.33 Å and transition region O V 629.73 Å emission lines over
a time period of ∼ 29 min are presented. One eruptive event was
detected in this time series of data. The parameters of the network
eruptive event are derived and the type of this small-scale activity
is identified. The lifetime of the event was ∼ 1 min and it was
found only in the transition region emission line. This event had no
chromospheric counterpart. All O V spectral profiles of the eruptive
event were blueshifted and the maximal Doppler shift was -14.7 km
s-1. During an initial phase of the eruptive event, the
O V intensity enhancement factor was 2.3. These parameters indicate
that the observed event could be a transition region explosive event
but measured with the limited resolution of the CDS instrument.
Title: Line intensities of chromospheric and photospheric spectra
of a flare
Authors: Brčeková, K.; Kučera, A.; Hanslmeier, A.; Rybák, J.;
Wöhl, H.
Bibcode: 2002ESASP.506..557B
Altcode: 2002ESPM...10..557B; 2002svco.conf..557B
In this work we present the intensities of spectral lines determined
from the time series of high resolution spectra obtained during
the relaxing phase of subflare. The spectra were taken in the core
of chromospheric Ca II K line and in two photospheric Fe I 522.5 nm
and Fe I 557.6 nm lines. It is shown, that the energy of the flaring
chromosphere slightly affects the underlying photospheric layers by
heating a small area right under the core of the subflare.
Title: Two-dimensional spectroscopic time series of solar granulation:
evolution of individual granules
Authors: Hanslmeier, Arnold; Kučera, Ales; Rybák, Jan; Wöhl,
Hubertus
Bibcode: 2002ESASP.506..633H
Altcode: 2002svco.conf..633H; 2002ESPM...10..633H
In this paper we investigate the dynamics of the solar granulation by
analyzing time series of 2-D spatially highly resolved spectrograms. The
high quality of the data permitted us to follow the evolution of
individual granular and intergranular areas. We used scans over the
solar surface in order to obtain a 2-D information. This has the
advantage of achieving high spectral and spatial resolution, however
one scan lasted for about 2 min.
Title: Cycle dependence of hemispheric activity
Authors: Temmer, M.; Veronig, A.; Rybák, J.; Hanslmeier, A.
Bibcode: 2002ESASP.506..859T
Altcode: 2002ESPM...10..859T; 2002svco.conf..859T
Data of daily hemispheric Sunspot Numbers are analyzed including the
time span 1975-2001. The study of north-south asymmetries concerning
solar activity and rotational behaviors is in particular relevant,
as it is related to the solar dynamo and the generation of magnetic
fields. As diagnostic tools we use wavelets and autocorrelation
functions in combination with statistical significance tests that are
applied separately to the northern and southern hemisphere. Pronounced
differences between the northern and southern rotational periods
are obtained. The northern hemisphere shows a rigid rotation of ~27
days which can be followed up to ~15 periods in the autocorrelation
function. The signal of the southern hemisphere is strongly attenuated
after 3 recurrences showing variable periods in the range ~26-28.5
days. The presence of these periods is not permanent during a cycle
suggesting activity pulses in each hemisphere. For the northern
hemisphere strong relations to the motions of deeper lying convective
structures building up long-living 'active zones' are suggested.
Title: Line-of-sight velocity in a semiempirical model of a
disappearing granule
Authors: Koza, J.; Bellot Rubio, L. R.; Kučera, A.; Hanslmeier, A.;
Rybák, J.; Wöhl, H.
Bibcode: 2002ESASP.506..443K
Altcode: 2002svco.conf..443K; 2002ESPM...10..443K
The behaviour of the line-of-sight velocity in the centre of a
disappearing granule is analyzed using an inversion method applied
to a time-series of spectra containing the Fe I 522.5 nm, 557.6
nm and 557.7 nm lines. The temporal evolution of the line-of-sight
velocity vLOS is presented in the form of the functional
dependence of vLOS(logτ5, t) on the optical
depth τ5 at 500 nm and time t. An oscillatory behaviour
is found in the velocity stratification with nearly constant phase
through the photosphere. The amplitude of variations increases from
logτ5 = -0.3 to logτ5 = -2.5 reaching a maximum
of ~1.2 km s-1. A zero velocity layer is detected in every
instantaneous model of the velocity stratification. The results suggest,
that the zero velocity may occur in a considerable range of the optical
depths from logτ5 ~ -2 to logτ5 ~ -3.5.
Title: Long-term periodicities in the flare index between the years
1966 - 2001
Authors: Özgüç, A.; Ataç, T.; Rybák, J.
Bibcode: 2002ESASP.506..709O
Altcode: 2002svco.conf..709O; 2002ESPM...10..709O
A brief description and the results of the temporal variability
of the flare index over the epoch of almost 4 cycles (1966-2001)
are presented. Using Fourier and wavelet transforms the long-term
periodicities in the daily flare index data for the total surface
and for the northern and the southern hemispheres of the Sun are
presented. A significant variability was found for all periods. The
wavelet transform results show that the occurrence of flare index
power is highly intermittent in time.
Title: Precise reduction of solar spectra obtained with large
CCD arrays
Authors: Wöhl, H.; Kučera, A.; Rybák, J.; Hanslmeier, A.
Bibcode: 2002A&A...394.1077W
Altcode:
A precise procedure suitable for the reduction of solar spectra
taken with large CCD arrays and the retrieval of correct spectral
characteristics is presented. Various effects, which one should take
into account, are considered and several improvements of the standard
reduction are introduced. A special flat-field procedure is suggested
for the reduction of spectra registered in different flat-field
conditions than those when the flat-field matrix was taken. The original
flat-field matrix is split into several components to eliminate the
influence of the drift of the spectrograph and temporal changes of
the flat-field conditions on the reduced spectrum. The importance
of every flat-field matrix component is tested and discussed and the
noise propagation through data reduction is analyzed. It is documented
that the errors of the basic spectral line characteristics, continuum
intensity, line centre intensity and full width at the half maxima
of the line have variations between 0.5% and 15% and the errors of
the line centre Doppler velocity and bisectors fluctuate by up to 200
m s-1, if derived from imprecise reductions, compared to
precise ones.
Title: Temporal evolution of physical parameters in granule
Authors: Koza, J.; Kucera, A.; Hanslmeier, A.; Rybák, J.; Wöhl, H.
Bibcode: 2002ESASP.505..457K
Altcode: 2002solm.conf..457K; 2002IAUCo.188..457K
The temporal evolution of the physical parameters inside a granule
is presented. This is a step towards a more realistic 1D modeling
of the solar granulation, avoiding the temporal averaging used up
to now. The granulation is treated as a dynamical phenomenon and our
model has been calculated using an inversion method applied to time
series of spectra. The granular evolutionary model is presented in
the form of the functional dependence of temperature T(log τ, t) and
line-of-sight velocity vLOS(log τ, t) on optical depth τ
and time t. The observed disappearance of the granule is accompanied
with significant temperature changes greater than ~300K in deeper layers
(log τ5 > 0) and upper layers (log τ5 <
-2.5). In contrary, the layers from log τ5 ~= -0.5 to log
τ5 ~= -1.5 are more stable in the sense of temperature
variations, which are less than ~150K. An oscillatory behavior is
found in the line-of-sight velocity stratification from log τ5 ~= 0
upwards with increasing amplitude reaching up to ~= 2 km s-1
in upper layers.
Title: Dynamic coupling of the chromospheric and photospheric
flaring plasma
Authors: Brceková, K.; Kucera, A.; Hanslmeier, A.; Rybák, J.;
Wöhl, H.
Bibcode: 2002ESASP.505..357B
Altcode: 2002solm.conf..357B; 2002IAUCo.188..357B
The relaxing phase of the subflare observed in the core of chromospheric
Ca II K line and in two photospheric Fe I 522.5 nm and Fe I 557.6 nm
lines was investigated. The temporal evolution of asymmetry in Ca II
K line and the mean bisectors positions of the Fe I line profiles as
well as their correlations are presented. It is documented that the
chromospheric down-flow caused by the subflare strongly affects the
upper layers of the photosphere. As a consequence of relaxation of
the photospheric layers strong down-flows and up-flows were measured
at the end of the subflare relaxing phase.
Title: High-resolution CCD spectra reduction: temporal changes of
the flat-field compensation
Authors: Kučera, Aleš; Hanslmeier, Arnold; Rybák, Ján; Wohl,
Hubertus
Bibcode: 2002NCimC..25..703K
Altcode:
A new method suitable for long-time series of high-resolution CCD
spectra reduction is presented. The method allows to compensate the
temporal changes of the instrument conditions which leads to temporal
changes of the flat-field matrix. Sometimes it is impossible to make
the flat-field measurements during long simultaneous observations with
satellites (SOHO, TRACE). The method splits the flat-field matrix into
two components. The first one, connected with CCD camera is stable in
time and is correct for all spectra. The second one varies and reflects
temporal changes of the conditions in the spectrograph. Description
of the method and its application to real high-resolution CCD spectra
is presented and discussed.
Title: Flare index variability in the ascending branch of solar
cycle 23
Authors: Özgüç, A.; Ataç, T.; Rybák, J.
Bibcode: 2002JGRA..107.1146O
Altcode:
A brief description and the results of the determination of the flare
index as a measure of solar activity on the ascending branch of cycle 23
up to 31 December 2000 are presented. The patterns of similar activity
indices that arise under different physical conditions during the rising
activity phase are compared with the flare index. All studied solar
indices rise more slowly in the current cycle than the last one, except
the total solar irradiance. The intermediate-term periodicities in the
daily flare index data were studied using the Fourier transform, and
it was found that the 35-, 62-, 116-, 198-, and 276-day periodicities
are in operation during the ascending branch of cycle 23. Contrary to
the previous three cycles, 155-, 73-, or 51-day periodicities were not
detected by the Fourier transform in this branch of the cycle. The
wavelet transform results show that the occurrence of flare index
power is highly intermittent in time, and the most pronounced power
peaks were found to be present at 35 days (the temporal locations at
1998.3, 1999.9, and 2000.5 years), 116 days (the temporal interval
1999.7-2000.4 years) and 276 days period (interval roughly from 1999.5
until the end of the flare index data). Comparison of the Fourier and
wavelet transform results has clarified the importance of different
periodicities, whether they are (62, 198 days) or are not (35, 116,
276 days) the harmonics of the basic ones, as well as the temporal
location of their occurrence.
Title: Transition region dynamics from SUMER/SOHO observations:
shape of the emission spectral lines
Authors: Rybák, J.; Curdt, W.; Kučera, A.; Wöhl, H.
Bibcode: 2002ESASP.477..163R
Altcode: 2002scsw.conf..163R
The quiet sun network/internetwork transition region line profiles
of C II 1036.34 Å and O VI 1037.61 Å are outlined emphasizing
the temporal/spatial behaviour of their deviations from the
Gaussian shape. Systematic deviations of the line profiles from the
single-Gaussian shape indicate that transition region emission lines
consist of two Gaussian components over almost the whole quiet sun
internetwork except their small innermost parts. This finding is in
qualitative agreement with the transition region model of Peter (2001).
Title: The North-South asymmetry of solar activity
Authors: Badalyan, O. G.; Obridko, V. N.; Rybák, J.; Sýkora, J.
Bibcode: 2002ESASP.477..201B
Altcode: 2002scsw.conf..201B
In the present paper the North-South (N-S) asymmetry of four solar
activity indices is estimated and discussed. The coronal green line
intensity measurements, the Wolf numbers and the sunspot area data
- all of them were subjected to analysis over the 1943-1999 period,
together with the NSO/KP data on the total magnetic field flux measured
from 1975. The pair comparison of these four indices within different
zones of solar latitude allowed to reveal a number of features in
their mutual correlativness. As the coronal green line intensity as
the sunspot area display a long-termed wave in their N-S asymmetry -
about 40 years in duration. While during the first half of the interval
studied the N-hemisphere dominates (with a clear maximum around 1964-66)
then during the second half of the interval the activity measured over
the S-hemisphere prevails. Quasi-biennial variations were identified
both in the N-S asymmetry of the coronal green line brightness and
that of the total magnetic flux. The performed study indicates a close
relation between the global and local manifestations of solar activity,
which are governed by the magnetic fields of different scales.
Title: Time Evolution of low-Frequency Periodicities in Cosmic
ray Intensity
Authors: Kudela, K.; Rybák, J.; Antalová, A.; Storini, M.
Bibcode: 2002SoPh..205..165K
Altcode:
The long-time series of daily means of cosmic-ray intensity observed by
four neutron monitors at different cutoff rigidities (Calgary, Climax,
Lomnický Štít and Huancayo/Haleakala) were analyzed by means of
the wavelet transform method in the period range ∼ 60 to ∼ 1000
days. The contributions of the time evolution of three quasi-periodic
cosmic-ray signals (∼ 150 d, ∼ 1.3 yr and ∼ 1.7 yr) to the
global one are obtained. While the ∼ 1.7-yr quasi-periodicity, the
most remarkable one in the studied interval, strongly contributes to
the cosmic ray intensity profile of solar cycle 21 (particularly in
1982), the ∼ 1.3-yr one, which is better correlated with the same
periodicity of the interplanetary magnetic field strength, is present
as a characteristic feature for the decreasing phases of the cycles
20 and 22. Transitions between these quasi-periodicities are seen in
the wavelet power spectra plots. Obtained results support the claimed
difference in the solar activity evolution during odd and even solar
activity cycles.
Title: Temporal Variability of the Coronal Green-Line Index
(1947-1998)
Authors: Rybák, J.; Dorotovič, I.
Bibcode: 2002SoPh..205..177R
Altcode:
Temporal variability of the coronal index - the `Sun as a star' coronal
green-line irradiance - is presented using wavelet transform over
the epoch of almost 5 solar cycles. A significant index variability
was found for all periods, particularly for the periods of 150 days
and 1 year as well as 28 days. Connection of the variability with the
phase of solar magnetic activity is outlined. The enhanced power of
the 150-day period is dominant before and after the magnetic activity
maxima in four out of the five cycles analyzed. To the contrary, no
enhanced power was found just during the maxima of all cycles for this
period. No clear periodic power behavior was found for the periods at
about one year. Substantial rotation period variations of the coronal
index up to 5 days take place over relatively short time intervals. A
comparison of the results of the Fourier transform and the time-period
wavelet transform of the coronal index time series shows that only the
application of the wavelet analysis enables one to find the relation
between the coronal index variability and the course of the magnetic
activity of the Sun.
Title: Comparing wavelet and traditional studies in the Gnevyshev
Gap context
Authors: Storini, M.; Laurenza, M.; Rybak, J.; Antalova, A.; Kudela, K.
Bibcode: 2002cosp...34E2174S
Altcode: 2002cosp.meetE2174S
As it is now well established the Gnevyshev Gap is a significant
phenomenon of the solar activity maxima (e.g. [1-3]) and Wavelet
Transform Method allows to investigate non-stationary processes
containing multi-scale features. Results from such kind of method
applied to several parameters of the Solar-Terrestrial System are
used together with the ones from traditional investigation methods to
better understand controversial findings obtained during the maximum
phase of the last four solar activity cycles. [1] F. Feminella and
M. Storini (1997), Astron. Astrophys. 322, 311. [2] G.A. Bazilevskaya
et al. (2000), Solar Phys. 197, 157. [3] M. Storini et al. (2002),
Adv. Space Res., in press.
Title: Temporal variability of the flare index (1966-2001)
Authors: Ozguc, A.; Atac, T.; Rybak, J.
Bibcode: 2002cosp...34E.511O
Altcode: 2002cosp.meetE.511O
A brief description and the results of the temporal variability of the
flare index over the epoch of almost 4 cycles are presented. Using
Fourier and wavelet transforms the long, the intermediate and the
short-term periodicities in the daily flare index data for the total
surface and for the northern and the southern hemisphere of the Sun were
presented. A significant variability was found for all periods. The
wavelet transform results show that the occurrence of flare index
power is highly intermittent in time. A comparison of the results of
the Fourier transform and the time-period wavelet transform of the
flare index time series has clarified the importance of different
periodicities, whether they are or are not the harmonics of the basic
ones, as well as the temporal location of their occurrence.
Title: On the quasi-biennial modulation of galactic cosmic rays
Authors: Storini, M.; Rybak, J.; Antalova, A.; Kudela, K.
Bibcode: 2001ICRC....9.3768S
Altcode: 2001ICRC...27.3768S
Results from the wavelet power spectrum (WPS) analysis of the cosmic
ray intensity, registered by the Calgary neutron monitor from 1969 to
1998 years, are used to discuss the characteristic behaviour of the
quasi-biennial modulation of galactic cosmic rays during solar activity
cycles n. 21 and n. 22. Results from the temporarily averaged global
power spectra (GPS) are also shown.
Title: On the wavelet approach to cosmic ray variability
Authors: Kudela, K.; Storini, M.; Antalova, A.; Rybák, J.
Bibcode: 2001ICRC....9.3773K
Altcode: 2001ICRC...27.3773K
A wavelet transform (time scale ~60 to ~1000 days) is applied on the
long-term time series of daily means of cosmic ray intensity observed
by neutron monitors at different cutoff rigidities. No persistent
periodicities with the same amplitude are found for the whole period
analyzed. The temporal evolution of quasiperiodic variations at
~150 days, ~1.3 years and ~1.7 years is examined. While the ~1.7-y
quasiperiodicity (the most remarkable one in the studied interval) is
strongly contributing to the cosmic ray intensity profile of solar cycle
21 (particularly in 1982), the ~1.3-y one (which is better correlated
with the same periodicity of the interplanetary magnetic field strength)
is a characteristic feature for the decreasing phases of the cycles 20
and 22. Transitions between them are seen from the wavelet power spectra
plots. Obtained results give a support to the claimed difference in
the solar activity evolution during odd and even solar activity cycles.
Title: The Solar and Cosmic-Ray Synodic Periodicity (1969 1998)
Authors: Antalová, A.; Kudela, K.; Rybák, J.
Bibcode: 2001SSRv...97..355A
Altcode:
The synodic recurrence of the Mt. Wilson plage index (MPSI) and the
Calgary cosmic ray (CR) intensity is investigated, using the wavelet
power spectra in the range of 18 38 days, during the last three solar
cycles. The unique temporal coincidence between the quasi synodic MPSI
and the CR periods is detected in 1978 1982 (the 21st solar cycle). In
the 22nd cycle there is a very strong MPSI synodic recurrence, from
1989.5 to 1990.5, but it is absent in the CR data. In 1992.5 1993.5
the MPSI and CR recurrence phenomenon is in good accordance with the
solar wind speed and cosmic ray modulation as measured during the
first Ulysses passage around the Sun. The Gnevyshev gap is present in
the 27-day recurrence of CR, in agreement with Kudela et al. (1999).
Title: The Location of Solar Oscillations in the Photosphere
Authors: Hanslmeier, A.; Kučera, A.; Rybák, J.; Wöhl, H.
Bibcode: 2001ASSL..259..267H
Altcode: 2001dysu.conf..267H
Applying a correlation analysis to time series of granulation it has
been shown that due to the influence of enhanced turbulent motions
near the downflow regions in the intergranular lanes the turbulent
motions predominate.
Title: Chromospheric Dynamics as can be Inferred from SUMER/SOHO
Observations
Authors: Rybák, J.; Kučera, A.; Curdt, W.; Schühle, U.; Wöhl, H.
Bibcode: 2001ASSL..259..247R
Altcode: 2001dysu.conf..247R
Experience with the SUMER/SOHO observations of the chromospheric
dynamics and the reduction of the acquired data is summarized on
base of the SOHO Joint Operation Program 78 which is focused on the
variability of the chromosphere and the transition region to the corona.
Title: The Wavelet Analysis of the Solar and Cosmic-Ray Data
Authors: Rybák, J.; Antalová, A.; Storini, M.
Bibcode: 2001SSRv...97..359R
Altcode:
Results of the wavelet power spectrum (WPS) analysis(which covers
the 1969 1998 years) obtained using the daily data of the following
parameters: (i) the Mt. Wilson Magnetic Plage Strength index (MPSI),
(ii) the solar LDE-type flare index (LDE-FI) and (iii) the Calgary
cosmic-ray (CR) intensity, are reported for periods ranging between
64 and 1024 days. The temporal distribution of the WPS during the
last three solar activity cycles is extremely discontinuous. A clear
resemblance between the CR and LDE-FI WPS is obtained only for the
22nd solar activity cycle. Nevertheless, the CR multiperiod peak,
observed in 1982, can well be identified with the WPS peaks obtained
in both solar parameters under consideration. In the 21st cycle, we
found significant the MPSI periods around 850 880 days (2.3 2.4 yr),
while such periods are present in the LDE-FI data of the 22nd cycle. In
the CR data we discerned a net periodicity around 650 days (1.7 yr).
Title: Dynamics of the Upper Photosphere: Coherence and Phase Analysis
(CD-ROM Directory: contribs/hanslmei)
Authors: Hanslmeier, A.; Kučera, A.; Rybák, J.; Wöhl, H.
Bibcode: 2001ASPC..223..669H
Altcode: 2001csss...11..669H
No abstract at ADS
Title: Correlative relationships in an inhomogeneous solar atmosphere
Authors: Gadun, A. S.; Hanslmeier, A.; Kučera, A.; Rybák, J.;
Wöhl, H.
Bibcode: 2000A&A...363..289G
Altcode:
We analyse the correlative relationships between various quantities
derived from 2-D inhomogeneous and time-dependent model atmospheres
and between selected simulated line parameters to compare them with
height-dependent correlations derived from spectral observations. We
detect three photospheric regions: thermal convection, overshooting
convection and a transition layer. We also show that correlations
found for the model data and those computed within simulated spectral
observations are a good testing tool for line formation depths. As
an example, we examine two criteria, providing heights of line core
formation in LTE, and conclude that the approach which defines
this quantity as geometrical height at line center optical depth
τλ0 = 1 is likely more suitable for diagnostic purposes
than the method based on depression contribution function.
Title: Dynamics of the upper solar photosphere
Authors: Hanslmeier, A.; Kučera, A.; Rybák, J.; Neunteufel, B.;
Wöhl, H.
Bibcode: 2000A&A...356..308H
Altcode:
The dynamics of the upper solar photosphere was studied by using
1-D photospheric line spectrograms obtained using the VTT of the
Observatorio del Teide. Three spectral lines with line core formation
heights between 250 and 500 km were analyzed. It is clearly seen that at
these levels the velocity and intensity fields are highly correlated
but different from the lower lying zone where convective motions
predominate. This is shown by classical methods (using correlations and
bisectors) as well as by applying the Hurst exponent method to the data.
Title: 3-D Tomography of the Solar Photosphere
Authors: Hanslmeier, A.; Kucera, A.; Rybak, J.; Wohl, H.
Bibcode: 2000ESASP.463..333H
Altcode: 2000sctc.proc..333H
No abstract at ADS
Title: On the Rotation Period of the Green Corona
Authors: Rybak, J.
Bibcode: 2000HvaOB..24..135R
Altcode:
The rotation period of the solar emission corona was determined using
the Fe XIV 530.3 nm coronal line measurements for the epoch 1947 -
1991 via the tracer method. An optimized correlation analysis has been
applied together with a new reliability test for the determination
of the rotation. The time-latitudinal dependence of the green corona
rotation rate on the phase of the solar cycle shows a nearly rigid
latitudinal behaviour for few years before and during cycle minima and
it is rapidly changing to a differential rotation just after the onset
of a new solar cycle. This differential rotation profile prolongs till
the beginning of the descending phase of the cycle and then a slow
return to the rigid profile follows. Large variations of the green
corona rotation between these two extremes lead to the conclusion that
the overall latitudinal and temporal averages of the coronal rotation
period are not physically correct.
Title: Spectral Statistics of Fe I and Ca II K Lines in the Quiet
and Active Solar Atmosphere
Authors: Kucera, A.; Brcekova, A. K.; Hanslmeier, A.; Rybak, J.;
Woehl, H.
Bibcode: 2000HvaOB..24..111K
Altcode:
Based on two Fe I and Ca II K lines spectra obtained with high spatial
and spectral resolution we investigated some spectral characteristics
of these lines in quiet and active regions. In this paper we present
the behaviour of the central line intensities in different types of
solar activity. We discuss the obtained results and compare them with
the results reported by other authors.
Title: The Variations of the Solar Activity and the Low Rigidity
Cosmic Rays (1969-1998)
Authors: Antalová, A.; Kudela, Karel; Rybak, Jan
Bibcode: 2000ESASP.463..281A
Altcode: 2000sctc.proc..281A
No abstract at ADS
Title: Two Dimensional Spectral Time Series
Authors: Hanslmeier, A.; Kucera, A.; Rybak, J.; Woehl, H.
Bibcode: 2000HvaOB..24...81H
Altcode:
We analyze two dimensional time series of solar photospheric
spectrograms in order to study the dynamics of solar fine structures and
their evolution. The two dimensional images were obtained by scanning
over the photosphere. Spectrographic data of this type include a much
higher information than ordinary images.
Title: Interaction of Sunspots with the Surrounding Plasma - a
Progress Report
Authors: Woehl, H.; Rybak, J.; Kucera, A.
Bibcode: 2000HvaOB..24..119W
Altcode:
The historic development of the search for interactions of sunspots
and solar plasma around them was given in a contribution at the IVth
Hvar Astrophysical Colloquium (Woehl, 1997). It was concentrated on
the results of measurements and their reductions performed by Lustig
and Woehl (1993), showing a dependence of plasma velocity difference
in front and behind stable sunspots depending on their relative speed
within the plasma. Since the result obtained was not significant,
new attempts were started to use MDI/SoHO data and mainly to collect
data ourselves at telescopes and the horizontal spectrometer of the
Astronomical Institute of the Slovak Academy of Sciences in Tatranska
Lomnica, Slovakia. The main difference is that now the plasma velocity
data are gained by a matrix of fiber optics collecting light at several
positions around the sunspot. In addition the sunspot positions are
collected by a different telescope. The reductions of the sunspot
positions give very reliable rotation data and - as expected - very
small meridional motions, while the plasma velocity data are not yet
reliable. Attempts to improve this situation are described.
Title: Fe I and Ca II K Lines in Quiet and Active Regions
Authors: Kucera, A.; Brcekova, K.; Hanslmeier, A.; Rybak, J.; Wohl, H.
Bibcode: 2000ESASP.463..357K
Altcode: 2000sctc.proc..357K
No abstract at ADS
Title: The Intermittency of the Solar Intermediate-Term Periodicity
(1969-1998)
Authors: Rybák, J.; Antalova, Anna; Storini, Marisa
Bibcode: 2000ESASP.463..419R
Altcode: 2000sctc.proc..419R
No abstract at ADS
Title: Chromospheric and Transition Region Dynamics - Reasons
and Consequences of the Long-period Instrumental Periodicities
of SUMER/SOHO
Authors: Rybák, J.; Curdt, W.; Kucera, A.; Schühle, U.; Wöhl, H.
Bibcode: 1999ESASP.448..361R
Altcode: 1999mfsp.conf..361R; 1999ESPM....9..361R
No abstract at ADS
Title: Chromospheric And Transition Region Dynamics - Reasons
and Consequences of the Short Period Instrumental Periodicities
of SOHO/SUMER
Authors: Rybak, Jan; Curdt, Werner; Kučera, Ales; Schüehle, Udo;
Wöehl, Hubertus
Bibcode: 1999ESASP.446..579R
Altcode: 1999soho....8..579R
The instrumentally caused oscillations of the spectral lines intensity
and velocity, determined with the SUMER spectrometer onboard SoHO, are
presented. On examples of two long-term measurements of O I, C II and O
VI lines, it is shown that the reason of this instrumental effect was
the insufficient precision of the solar rotation compensation of the
spectrometer slit position. In both observational runs the standard
rotation compensation procedure, performed on-line by the instrument,
was selected for the long-term observations. The minor periodical
motion of the slit position on the solar disk was taking place during
such observations and this effect produced the regular changes of the
measured line intensities and velocities. The significant enhancements
of the oscillations amplitudes around the frequency 2.56 mHz and its
harmonics were detected in the cases of observations, performed at
the disk center. Unfortunately, these frequencies are just in the
range of the typical oscillations determined till now in the upper
solar atmosphere ! Consequences of this instrumental effect for SUMER
measurements of the chromospheric and transition region dynamics
are discussed. Procedures how to exclude the effect from the data
post-facto as well as how to modify the future SUMER oscillations
measurements in order to avoid the effect are proposed
Title: Fiber Optics Device for Solar Spectroscopy - First Measurements
Authors: Kucera, A.; Rybák, J.; Wöhl, H.; Hanslmeier, A.
Bibcode: 1999ASPC..184..319K
Altcode:
In 1996 we introduced the fiber optics device designed for 2D
solar spectroscopy (Kucera et al. 1997). Now we present the first
results obtained within last year. First experiences with wavelength
calibration, light transmission through the fibers, noise reduction,
software for reduction of observations and preliminary results of
reduced scientific data are presented.
Title: SOHO JOP 078 - variability and properties of the quiet sun
supergranular network and internetwork.
Authors: Kučera, A.; Curdt, W.; Fludra, A.; Rybák, J.; Wöhl, H.
Bibcode: 1999joso.proc..149K
Altcode:
Study of the variability of the quiet solar atmosphere covering as
large as possible range of the temperatures using both the 2D imaging
and 1D spectra was the aim of SOHO JOP 78 observations. Supergranular
cells were the objects of the authors' main interest. This programme is
based on the cooperation of several SOHO instruments (SUMER, CDS, MDI,
EIT) and TRACE. Justification of the JOP, cooperation of instruments
and specially arranged measurements for the post-facto coalignment of
data from different instruments are described in this paper.
Title: Correlation of Velocity Fields at Different Heights in the
Solar Photosphere
Authors: Kucera, A.; Rybák, J.; Wöhl, H.
Bibcode: 1999ASSL..239..219K
Altcode: 1999msa..proc..219K
A simple experimental method for comparison of the line formation
heights in the solar photosphere is presented. Several Fe I lines are
used to test the method.
Title: Heights of formation of FeI photospheric lines
Authors: Kucera, A.; Balthasar, H.; Rybak, J.; Woehl, H.
Bibcode: 1998A&A...332.1069K
Altcode:
The determination of the location of spectral line-forming layers
by means of line-depression contribution functions is checked by
observational tests. The method is based on the assumption that the
Doppler velocities derived from line bisectors at a given position in
the profile of a spectral line are related to the actual bulk velocity
at a particular height in the atmosphere. For a set of six magnetically
sensitive and non-sensitive Fe I lines (543.45, 557.61, 630.15, 630.25,
649.50, 649.45 nm) the fluctuations of Doppler velocities along the slit
of the spectrograph were determined at various Delta lambda from the
line centers i.e. at various heights in the photosphere. Correlations
of fluctuations allow us to find those parts in line profiles which
are formed at identical heights in the photosphere. These experimental
results are compared with theoretical estimates based on line depression
contribution functions. The agreement is good and best results are found
for nonmagnetic strong, but still unsaturated lines. The results support
the hypothesis that it is possible to ascribe a single height point
in the solar atmosphere to a given position in a spectral line profile.
Title: Oscillations in Chromosphere and Transition Region Based on
SUMER Measurements
Authors: Kucera, A.; Curdt, W.; Rybák, J.; Schühle, U.; Wöhl, H.
Bibcode: 1998ASPC..155..351K
Altcode: 1998sasp.conf..351K
No abstract at ADS
Title: Behaviour of solar active prominence
Authors: Kučera, A.; Rybák, J.; Saniga, M.
Bibcode: 1998PAICz..88..232K
Altcode:
No abstract at ADS
Title: Measurement of rotational characteristics of sunspots and
surrounding photospheric plasma.
Authors: Kučera, A.; Rybák, J.; Wöhl, H.
Bibcode: 1997joso.proc...68K
Altcode:
No abstract at ADS
Title: Investigation of the Dynamics of Chromosphere and Photosphere
from Spectra Obtained by Parallel Observations using SUMER on SOHO
and the VTT on Tenerife
Authors: Curdt, W.; Kucera, A.; Rybak, J.; Schuhle, U.; Wohl, H.
Bibcode: 1997ASPC..118..322C
Altcode: 1997fasp.conf..322C
This is a preliminary report about parallel observations of
chromospheric and photospheric spectra in the ultraviolet and visible
spectral regions using SUMER on SOHO and the VTT on Tenerife performed
begin of September 1996. The aim is to search for relations of vertical
velocity patterns in the upper photosphere and chromosphere in the
solar disk center. In addition temporal changes in these parts of the
solar atmosphere are investigated.
Title: Dynamical Properties of the Chromosphere and Transition Region
in the Supergranular Network: What Precision of the Spectral Line
Characteristics Can be Reached?
Authors: Curdt, W.; Kucera, A.; Rybák, J.; Schühle, U.; Wöhl, H.
Bibcode: 1997ESASP.404..307C
Altcode: 1997cswn.conf..307C
No abstract at ADS
Title: Long Duration Soft X-ray Events and Galactic Cosmic Ray
Modulation
Authors: Antalova, A.; Rybak, J.; Kudela, K.; Venkatesan, D.
Bibcode: 1996ASPC...95..119A
Altcode: 1996sdit.conf..119A
No abstract at ADS
Title: Rotation of the solar green corona - Tracer results and
their reliability
Authors: Rybak, J.
Bibcode: 1996ASPC..109..157R
Altcode: 1996csss....9..157R
No abstract at ADS
Title: Results of the 1994 and 1995 Eclipse Observations
Authors: Sýkora, I.; Ambros, P.; Kotrc, P.; Minarovjech, M.; Pintér,
T.; Rybák, J.; Rybanský, M.
Bibcode: 1996RoAJ....6...21S
Altcode:
No abstract at ADS
Title: On the correlation between daily GCR intensity values and
LDE-type flare index (1987, 1988, 1990 and 1992)
Authors: Antalova, A.; Kudela, K.; Venkatesan, D.; Rybak, J.
Bibcode: 1995AdSpR..16i.233A
Altcode: 1995AdSpR..16..233A
The correlation analysis between daily values of Calgary Galactic
Cosmic Ray intensity (CNI) and LDE-type flare index (FI) reveals
the following results: in all years under consideration, the CNI-FI
anticorrelation is small, but statistically significant. The yearly
CNI-FI trend depends on yearly heliospherical conditions and on their
22-year cyclical changes. At the onset of the 22-nd cycle (in 1987) the
CNI-FI relation had broad minimum, similar to the result for non-flare
SXR background corona in 1987. In 1988 and 1992 the typical short-term
CNI-FI lag (from - 1 to - 3 days) was found, indicating the presence
of local heliospherical CNI modulation sources. In 1990, the CNI-FI
correlation has two comparable, large minima at - 22 as well as -
9 day CNI lags. Such double peak form of the 1990's CNI-FI minimum
is consistent with the existence of two, amplitudinally balanced CNI
modulation sources in the 1990's heliosphere. The first source seems
to be a substantial Global Merged Interaction Region (GMIR) located
in the outer heliosphere (producing the - 22 day CNI lag). The second
source was a typical local heliospherical structure, indicated by
short-term CNI lags.
Title: Daily values of the solar SXR background and modulation of GCRs
(1987, 1988, 1990 and 1992)
Authors: Antalova, A.; Kudela, K.; Venkatesan, D.; Rybak, J.
Bibcode: 1995AdSpR..16i.237A
Altcode: 1995AdSpR..16..237A
We present here the results of the intercorrelation analysis between
the daily Calgary Galactic Cosmic Ray intensity values (CNI) and daily
solar SXR background (XBG - unresolved full-sun SXR GOES flux). The
anticorrelation between CNI and XBG is statistically significant
for 1987, 1988 and 1992 sequences. In 1990, no anticorrelation
between CNI and XBG was found. The latter fact gives evidence for
the Global Merged Interaction Region (GMIR) being the most dominant
GCR modulation structure of the 1990's outer heliospherical system,
while local heliospherical structures seemed to play the secondary role.
Title: Observations of Fe I lines in the quiet solar photosphere.
Authors: Kucera, A.; Rybak, J.; Woehl, H.
Bibcode: 1995A&A...298..917K
Altcode:
We investigate three sets of spectra with high spatial and spectral
resolution. Each set consists of four spectra taken simultaneously
with the Vacuum Tower Telescope at Izana, Tenerife. The main spectral
characteristics (continuum intensity I_c_; full width at half
maximum FWHM; residual intensity I_o_) were computed for 5 magnetic
and non-magnetic Fe I lines (5434.543 A, 5576.099 A, 6301.497 A,
6302.499 A, 6494.994 A). Our results allow a diagnosis of the solar
atmosphere in the vertical (two main levels of line formation)
and horizontal directions (71 arcseconds). The spectra cover both
interior parts of supergranular cells (purely quiet regions, PQR) and
cell boundaries (moderate active regions, MAR). The main results are:
(1) We find a different continuum intensity distribution for PQRs
and MARs, which reflects the existence of different patterns in these
regions. The difference is also evident in the rms residual intensity
fluctuation. (2) A significant minimum of the residual intensity
fluctuations (δI_o_/I_c_)_rms_ occurs at a height of about 300km. (3)
At all heights of the PQRs the line widths FWHM in the intergranular
lanes are larger than the mean line width; those in the granules
are smaller. This variation of the FWHM is influenced by a magnetic
effect near the centres of the intergranular lanes (reduced FWHM),
and by the effect of convection in granules (enhanced FWHM). (4)
The correlation <I_c_, I_o_> reverses its sign at a height of
about 250km. The anticorrelation in the range 300-500km indicates a
non-convective structure, different from the photospheric granular
pattern found earlier.
Title: Daily Values of the Solar SXR Background and Galactic Cosmic
Ray Modulation (1968-1972)
Authors: Antalová, A.; Rybák, J.; Kudela, K.; Venkatesan, D.
Bibcode: 1995ICRC....4..534A
Altcode: 1995ICRC...24d.534A
No abstract at ADS
Title: Role of LDE-Type Flares in the GCR Modulation (1969-1972)
Authors: Antalová, A.; Rybák, J.; Kudela, K.; Venkatesan, D.
Bibcode: 1995ICRC....4..530A
Altcode: 1995ICRC...24d.530A
No abstract at ADS
Title: Cosmic-Ray Modulation and Long-Duration Solar Flare Events
Authors: Kudela, K.; Antalova, A.; Venkatesan, D.; Rybak, J.
Bibcode: 1994SoPh..154..371K
Altcode:
The correlation between the long-term intensity variations of cosmic
rays at neutron monitor energies and the LDE index measure of solar
flares with long-lasting soft X-ray emissions is reported. Three
subsequent solar cycles, 20-22, are taken into account and half-monthly
data are analyzed. Possible explanation of this correlation is discussed
in terms of the recent concepts of cosmic-ray modulation, in particular
with merged interaction regions affecting the cosmic-ray intensity.
Title: Rotational characteristics of the green solar corona: 1964 1989
Authors: Rybak, J.
Bibcode: 1994SoPh..152..161R
Altcode: 1994svs..coll..161R; 1994IAUCo.143..161R
Fe XIV 5303 å coronal emission line observations have been used for
the estimation of the rotation behaviour of the green solar corona. A
homogeneous data set, created from measurements carried out within the
framework of the world-wide coronagraphic network, has been examined
with a correlation analysis to reveal the averaged synodic rotation
period as a function of latitude and time over the epoch from 1964
to 1989.
Title: Long Duration Solar Flare Events and Cosmic Ray Modulation
(1969-1992)
Authors: Antalova, A.; Kudela, K.; Venkatesan, D.; Rybak, J.
Bibcode: 1994scs..conf..499A
Altcode: 1994IAUCo.144..499A
The authors present the results of a correlation analysis between the
galactic cosmic ray intensity decrease (as observed on Calgary neutron
monitor station) and the occurrence of SXR long-lasting (LDE-type)
solar flares represented by the LDE-type flare index FI. It is shown,
that for the solar cycle with the lower monthly values of FI (the
21-st solar cycle) the correlation coefficient is slighter (about 0.4)
as compared to the cycles with the higher LDE-type flare activity
(about 0.6, in the 20-th and the 22-nd cycles).
Title: Rotational Characteristics of the Green Solar Corona: 1947-1991
Authors: Rybak, J.; Rusin, V.; Rybansky, M.
Bibcode: 1994scs..conf..139R
Altcode: 1994IAUCo.144..139R
Fe XIV 530.3 nm coronal emission line observations have been used for
the estimation of the green solar corona rotation. A homogeneous data
set, created from measurements of the world-wide coronagraphic network,
has been examined with a help of correlation analysis to reveal the
averaged synodic rotation period as a function of latitude and time
over the epoch from 1947 to 1991.
Title: FeXIV Line Emission Polarization of the July 11, 1991 Solar
Corona
Authors: Sykora, J.; Rybak, J.; Ambroz, P.
Bibcode: 1994scs..conf..541S
Altcode: 1994IAUCo.144..541S
High resolution images, obtained during July 11, 1991 total solar
eclipse, allowed to estimate the degree of solar corona polarization
in the light of Fe XIV 530.3 nm emission line and in the white light,
as well. Very preliminary analysis reveals remarkable differences in
the degree of polarization for both sets of data, particularly as for
level of polarization and its distribution around the Sun's limb.
Title: Mass Ejections from Chromosphere to Corona: Results from a
Spectral Analysis
Authors: Kučera, A.; Rybák, J.; Minaroviech, M.
Bibcode: 1994emsp.conf..147K
Altcode:
No abstract at ADS
Title: Magnetic and nonmagnetic line profiles in solar quiet and
active regions
Authors: Kučera, A.; Rybák, J.; Wöhl, H.
Bibcode: 1994smf..conf..291K
Altcode:
No abstract at ADS
Title: IBM PCs also for the Solar Observations with Adaptive Optics?
Authors: Ambrôz, J.; Rybák, J.
Bibcode: 1994ESOC...48..167A
Altcode: 1994aao..conf..167A
No abstract at ADS
Title: A new instrumentation project for the Lomnicky stit coronal
station
Authors: Rybak, J.
Bibcode: 1993CoSkS..23..129R
Altcode:
A proposal of a new telescope/auxiliary instrumentation system for the
solar coronal station at Lomnicky Stit (2632 m asl) is described in
both the general concept and some particular technical details. The
main aim of the system is to observe the near-limb photospheric and
chromospheric layers of the solar atmosphere by the white-light and
narrow-band imaging, as well as to perform the visible and near-infrared
spectroscopy and spectropolarimetry of the parts of solar disk already
mentioned. These sorts of data, measured simultaneously with the coronal
emission line profiles which are regularly obtained at this time by
coronagraph, could give us a great amount of physical information about
the solar activity events (such as the height distribution of energy,
mass, magnetic fields and their time evolution). The initial ideas and
motivation of the project are explained. The parameters of the system
components - refractors, narrow band filters, focal plane detectors
and fibre optics positioners, telescope-spectrograph coupling via
fiber optics, spectrographs, detectors and computers for the control of
observations and the data acquisition - are discussed. TV CCD detectors
connected with the advanced frame grabbers and the IBM PC computers are
especially taken into account for the data acquisition. We also briefly
mention advantages and disadvantages of the system as a whole. Finally,
the future prospects of the project proposal are briefly described.
Title: A new instrumentation project for the Lomnický štít
coronal station.
Authors: Rybák, J.
Bibcode: 1993CoSka..23..129R
Altcode:
No abstract at ADS
Title: Numerical analysis of a static cylindrically symmetric Abelian
Higgs sunspot
Authors: Klacka, J.; Saniga, M.; Rybak, J.
Bibcode: 1992CoSka..22..107K
Altcode:
We present the exact numerical solutions of the Ginzburg-Landau
equations for the case of a static, cylindrically symmetric Abelian
Higgs sunspot model. The method of solving of these equations is
presented in detail, and the behaviour of the Higgs field amplitude,
magnetic field strength, electric current density, as well as of the
diagonal components of the stress-energy tensor are illustrated for
spots carrying one to five flux quanta.
Title: The journey into the centre of the Sun.
Authors: Neslusan, L.; Rybák, J.
Bibcode: 1992Kozmo..23....8N
Altcode:
No abstract at ADS
Title: Hot mass transport in the solar active prominence
Authors: Kucera, A.; Saniga, M.; Rybak, J.
Bibcode: 1992AIPC..267..160K
Altcode: 1992ecsa.work..160K
On October 16, 1990, a remarkable active prominence was observed,
in Hα line, during 113 minutes. The time gap between successive
profile recordings was 20 seconds and 339 profiles have been recorded
together. We focused our attention on Doppler shift measurements as
well as on significant changes in the prominence intensity. We also
give a possible explanation of a sudden increment in the intensity of
Hα line in dependence on the fact if the whole profile originates in
one particular place in the prominence or if it is a superposition of
the radiation incident from two different, physically unrelated parts
of the prominence.
Title: The horizontal solar telescope with spectrograph at Stará
Lesná Observatory
Authors: Kucera, A.; Rybak, J.; Minarovjech, M.; Novocky, D.;
Saniga, M.
Bibcode: 1990Ap&SS.171..279K
Altcode:
The construction and the optical design as well as the controlling
electronic device and the spectrum recording of the new horizontal
solar telescope with the spectrograph of the Astronomical Institute of
Slovak Academy of Sciences are described. Also some of its adjustments
and improvements are briefly mentioned.
Title: Globules and star formation.
Authors: Rybák, J.
Bibcode: 1988Kozmo..19...11R
Altcode:
No abstract at ADS
Title: Can small-scale bipolar structures originate in the solar
atmosphere ?
Authors: Saniga, M.; Kučera, A.; Novocký, D.; Rybák, J.
Bibcode: 1986CoSka..15..683S
Altcode:
Using the formalism of the magnetohydrodynamics shock waves the simple
model of the origin of small-scale bipolar structures in a magnetized
plasma is outlined. It is shown that there are regions in the atmosphere
of the Sun where such object can naturally occur. Properties of these
structures and their typical dimension are examined.